Exhibit 16.1

Armanino LLP

2700 Camino Ramon, Suite 350

San Ramon, CA 94583

925 790 2600 main

925 790 2601 fax

Armanino.com

September 26, 2023

Securities and Exchange Commission

100 F Street, N.E.

Washington, DC 20549

Commissioners:

We have read Item 4.01 of the Current Report on Form 8-K of ACM Research, Inc. dated September 26, 2023, and agree with the statements concerning our firm contained therein. We have no basis to agree or disagree with other statements of the registrant contained therein.

Very truly yours,

/s/ Armanino LLP

San Ramon, California