The enzyme characteristics of endogenous protease were analyzed and the optimum autolysis conditions were determined by the orthogonal test. Result showed that the endogenous protease of Tilapia viscera was stable at pH of 5~11 and 40~50℃. The optimum conditions for autolysis of viscera were pH 8, temperature 45℃, raw/water materials 1:2 and reaction time 4 h, under which the nitrogen recovery ratio and degree of hydrolysis were 73.21% and 18.78% respectively.