BEIJING—U.S. businesses in China are voicing increased concern about unclear laws, perceived antiforeign sentiment and industrial overcapacity, adding to worries about uncertainty over the slowing Chinese economy.

An annual survey of members of the American Chamber of Commerce in China released Wednesday found that companies see the business environment getting tougher. Of the 496 companies that responded to the survey, about 57%—including those in technology, consumer and service sectors—say their top challenges in China...