The protein content and the molecular weight distribution of black-bone chicken peptides(BCP),black-bone chicken essence(BCE) and black-bone chicken soup(BCS) were compared in the paper.The results showed that the protein content of BCP was 84.18%,acid soluble protein content was 83.10%,both were much higher than that of in BCE and BCS.The molecular weight distribution study showed that the small molecular proportion of BCP was much higher than that of the BCE and BCS,the proportion of BCP molecular weight between 140 and 1000 which was easily to be absorbed by human was up to 92.59%.