Condensed financial information of the parent company - Statement of income and comprehensive income (Details) - USD ($)	12 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Operating Expenses [Abstract]
General and administrative	$ (1,467,373)	$ (981,347)	$ (515,596)
LOSS FROM OPERATIONS	5,534,520	7,042,653	3,521,519
NET INCOME	4,363,591	3,768,109	2,454,874
FOREIGN CURRENCY TRANSLATION ADJUSTMENT	(267,546)	133,553	(135,663)
COMPREHENSIVE INCOME	4,096,045	3,901,662	2,319,211
Reportable Legal Entities [Member] \| Parent Company [Member]
Operating Expenses [Abstract]
General and administrative	(309,466)	(115,683)	0
LOSS FROM OPERATIONS	(309,466)	(115,683)	0
EQUITY INCOME OF SUBSIDIARY	4,673,057	3,883,792	2,454,874
NET INCOME	4,363,591	3,768,109	2,454,874
FOREIGN CURRENCY TRANSLATION ADJUSTMENT	(267,546)	133,553	(135,663)
COMPREHENSIVE INCOME	$ 4,096,045	$ 3,901,662	$ 2,319,211

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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