This study investigated protease activities in different digestive organs of wild giant spiny frog (Quasipaa spinosa) in the range of pH 0.5 to 10.0 at 30℃ and reaction temperature 15 to 60℃ at optimum pH in vitro. The protease activity was measured using the Folin-phenol method. The data were statistically analyzed by One-way ANOVA and LSD. The results showed that pH could affect protease activities of esophagus, stomach and pancreas significantly (P < 0.05), and their dynamic curves of protease activities were typically unimodal with increasing pH (Fig. 1).The protease activities of esophagus, stomach, pancreas and intestine were maximal at pH 1.5, 1.5, 9.6 and 7.4, respectively. The protease activities of digestive organs showed an obvious temperature dependence (P < 0.05), and the curves were also typically unimodal (Fig. 2). The protease activities of esophagus, stomach, pancreas, foregut, hindgut and rectum attained maximum value at temperature 50℃, 50℃, 45℃, 45℃, 45℃ and 45℃, respectively. Under the conditions of 30℃ and optimal pH mentioned above, digestive organs were arranged in order of descending protease activities: pancreas, esophagus, stomach, rectum, foregut and hindgut. In conclusion, there obviously exists a regular protease distribution in digestive system of this species, and the enzymes from different organs can show maximal activities at specific pH values and temperatures.