Abstract: In order to explore the effects of combined enzymes on the taste-forming substances of the compound osteolysin hydrolysate of bovine osteoprotin and chicken osteoprotin, four combined enzymes (nematolyt+flavourzyme, bromelain+flavourzyme, alkaline proteinase+flavourzyme, protamex+flavourzyme) were made for compound osteolysin hydrolysates, and degree of hydrolysis, free amino acids, taste nucleotides, equivalent umami concentration (EUC), peptide molecular weight distribution and other taste substances indicators were measured and analyzed. The results showed that the maximum hydrolysis degrees of alkaline proteinase+flavourzyme (A+F) and protamex+flavourzyme (P+F) were 10.67% and 11.27%, respectively. The analysis of taste free amino acid composition found that the A+F enzymatic hydrolysate had the highest content of umami amino acids, bitter amino acids, and odorless amino acid. The total free amino acid content of the hydrolysis solution was the highest for A+F and P+F enzymes, while the inosinic acid content was the highest among the four hydrolysis solutions.The total nucleotide content of the A+F hydrolysis solution was the highest. A+F enzymatic solution had the highest EUC value. The molecular weight<1000 Da peptides of A+F and P+F enzymatic solutions was the highest. Principal component analysis showed that A+F combined enzyme had the highest comprehensive score, and A+F combined enzyme provided abundant reaction substrates for Maillard reaction.