The layoffs come as SoftBank tries to set up a public listing for Arm this year.
Before the layoffs, Arm China had about 700 employees; there were no layoffs last year when parent Arm Ltd had global layoffs affecting up to 15% of its workforce, according to one of the sources.
Arm China declined to comment.
Arm China is the exclusive distributor of Arm licenses in China.
One of the sources said some customers are concerned about Arm potentially changing how it charges royalties, as well as U.S.-China geopolitical tensions that could cut off access to Arm technology.