Objective To investigate the adulteration of using synthetic acetic acid in commercial vinegar in Hangzhou areas of Zhejiang province.Methods Samples were collected randomly from markets in Hangzhou area and analyzed for the ratio of brewing acetic acid in vinegar by the National Standard Method GB 1903—2008.Results The qualified rate for 51 brewing vinegar was 96.08% and that for 10 dispensing vinegar was 70.00%.Conclusions The adulteration of blending synthetic acetic acid into dispensing vinegar was more serious and the supervision on the adulterated vinegar should be strengthened to ensure the quality of food safety.