Abstract: Proteases was used to extract chitin from the shrimp shell. The hydrolysation conditions were studied, and the effect was evaluated by the hydrolysis rate. By comparing with different hydrolysis effects of proteases, it suggested that Alcalase shown the best hydrolysis effect. The optimized the hydrolysis reaction system was:5000U/g Alcalase, pH8.5, 60℃ for 6h, at the concentration of substrate 2g mass/100mL solution.The hydrolysis rate on the optimal system was 78.3%. Through the electron microscopy (SEM) scanning, the effect of the different methods to extract chitin was compared. The surface of chitin deproteinized by Alcalase was glabrous and different from the alkaline solution, which confirmed the enzymatic reaction system was successful.