The dissolution of the wool keratin has a history of several decades, but the effective dissolution method has not been found yet. In this article, a novel reducing agent TCEP (Tris (2-carboxyethyl) phosphine) was used, which has a strong ability for selective reduction of disulfide bonds. With a joint use of sodium bisulfite, the wool dissolution has a great advantage in wool processing compared with previous methods; Through amino acid analysis, it was found that the content of the cysteine decreased significantly when using the TCEP as reducing agent, and the other amino acids did not change significantly, indicating that TCEP has high selectivity for reduction of disulfide bonds, and plays a significant role to maintain the molecular weight of keratin. The efficiency of dissolution was greatly improved; dissolution time was 4h, dissolution rate was 93.6%, keratin concentration was 10%, the yield of keratin with the molecular weight more than 3500 and more than 8000 were 80% and 72% respectively. By using SDS-PAGE, we can get that the main molecular weight of the keratin was 14000-20000.