In this experiment, the bitter taste substances of cocoa beans at different baking temperatures were separated, and then analyzed. Based on the concept of sensory evaluation and relative flavor activity value, the main components involved in the formation of bitter taste of cocoa beans were screened out. The change rule of volatile substances of cocoa beans during baking was compared with the technology of pyrolysis GC-MS. The results showed that: ① there were 55 volatile components in the bitter and astringent flavor of cocoa bean extract, including 7 alcohols, 5 acids, 9 esters, 8 aldehydes, 6 ketones and 2 alkenes; ② the key components of bitter and astringent flavor were 2-methylpropionaldehyde, 2-methoxyphenol, 2-heptanol, glutaraldehyde, 2-pentanone, benzaldehyde, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, and the modified group can be divided into 3-methylbutanol, 2,3-dimethyl-5-ethylpyrazine, 2,5-dimethylpyrazine, 2,3-dimethylpyrazine and 2-methylpropanol; ③ 130~135 ℃ is the best baking temperature to reduce the bitter and astringent taste of cocoa bean.