NOTES PAYABLE (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Short-term Debt
Notes payable - bank acceptance notes	$ 9,425,071	$ 8,895,107
Restricted cash	$ 7,980,907	6,025,718
Bank fee percentage	0.05%
Principal amount on commission of issuance on restricted cash	$ 7,980,000.0000	6,020,000.0000
Bank Acceptance Note One [Member]
Short-term Debt
Notes payable - bank acceptance notes	$ 760,086
Repayment date	Dec. 16, 2021
Bank Acceptance Note Two [Member]
Short-term Debt
Notes payable - bank acceptance notes	$ 1,824,207
Repayment date	Sep. 07, 2021
Bank Acceptance Note Three [Member]
Short-term Debt
Notes payable - bank acceptance notes	$ 1,824,207
Repayment date	Sep. 07, 2021
Bank Acceptance Note Four [Member]
Short-term Debt
Notes payable - bank acceptance notes	$ 760,086
Repayment date	Apr. 09, 2021
Bank Acceptance Note Five [Member]
Short-term Debt
Notes payable - bank acceptance notes	$ 1,520,173
Repayment date	Mar. 27, 2021
Bank Acceptance Note Six [Member]
Short-term Debt
Notes payable - bank acceptance notes	$ 1,520,173
Repayment date	Mar. 18, 2021
Bank Acceptance Note Seven [Member]
Short-term Debt
Notes payable - bank acceptance notes	$ 1,216,139
Repayment date	Mar. 18, 2021
Bank Acceptance Note Eight [Member]
Short-term Debt
Notes payable - bank acceptance notes		$ 1,147,756
Repayment date		Sep. 05, 2020
Bank Acceptance Note Nine [Member]
Short-term Debt
Notes payable - bank acceptance notes		$ 3,443,266
Repayment date		Aug. 30, 2020
Bank Acceptance Note Ten [Member]
Short-term Debt
Notes payable - bank acceptance notes		$ 1,434,695
Repayment date		Jul. 15, 2020
Bank Acceptance Note Eleven [Member]
Short-term Debt
Notes payable - bank acceptance notes		$ 1,434,695
Repayment date		Jul. 12, 2020
Bank Acceptance Note Twelve [Member]
Short-term Debt
Notes payable - bank acceptance notes		$ 1,434,695
Repayment date		Sep. 05, 2020

Bank charges for commission on each transaction, stated as a percentage of the principal amount of notes payable.

No definition available.

Name:	osn_BankFeePercentage
Namespace Prefix:	osn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount represents the principal amount on commission of issuance of restricted cash.

+ References

No definition available.

+ Details

Name:	osn_PrincipalAmountOnCommissionOfIssuanceOnRestrictedCash
Namespace Prefix:	osn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Current portion of the total carrying amount as of the balance sheet date due within one year or the operating cycle, if longer, on all notes payable to banks paid on an installment with long term maturities. This can include the amount of any loans from the applicant firm. This does not, however, include any mortgage balances.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(a)(1),20)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_NotesPayableToBankCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as current. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121566466&loc=d3e6676-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3044-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=121583591&loc=SL98516268-108586

+ Details

Name:	us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShortTermDebtLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteSixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteSevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteEightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteTenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteElevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=osn_BankAcceptanceNoteTwelveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: