Abstract: In order to analyze the amino acid composition and variation of Pixian soybean paste during the post-fermentation process,its taste effect was evaluated based on the analysis of changes in amino acid nitrogen content,free amino acid content and ACE inhibitory peptide. The results showed that there were 20 kinds of amino acids in the Pixian soybean paste. With the extension of post-fermentation time,the content of amino acid nitrogen increased first and then decreased.The four amino acids with higher content(≥1.00 mg/g)in each stage of fermentation were aspartic acid,asparagine,glutamic acid and proline,and the total percentage was over 45.58%.According to the free amino acids,amino acids nitrogen and taste active values(TAVs)of Pixian soybean paste,there were no significant differences in amino acid nitrogen,free amino acid,and TAV values between 9 months and 2 years of the post-fermentation. During the post-fermentation period of Pixian soybean paste,the activity of ACE inhibitory peptide reached 83.90% at 2 months and the lowest value was still 70.13%,which might be related to the structure of ACE inhibitory peptides of soybean paste and its metabolic processes and succession processes among various microorganisms in the post-fermentation process.The study can provide a new way of thinking for the production enterprises to scientifically set the fermentation cycle and to dig and study the biological activity of the pixian soybean paste from the perspective of overall health.