In order to investigate the changes of organic acids and free amino acid during fermentation process of Sichuan bran vinegar, 7 kinds of organic acids and 17 kinds of free amino acid content were determined by high performance liquid chromatography (HPLC) and automatic amino acid analyzer. The results showed that during fermentation process, acetic acid and lactic acid were the main organic acids of Sichuan bran vinegar, and the contents increased significantly. The contents of oxalic acid, citric acid, tartaric acid, malic acid and succinic acid were low, and there was no obvious change. The contents of free amino acids increased significantly from 668 mg/100 g to 1 470 mg/100 g during the early stage. Among them, Asp, Ser, Glu, Gly, Ala, Val, His, Ile, Tyr, Pro gave a great contribution to the Sichuan bran vinegar.