Objective:To explore the optimum technological conditions for preparing collagen from brown frog(Rana Dybowskii) body by pepsin,and to determine the purity of collagen and contents of amino acids. MethodsBy determining extraction rate,single-factor trials and orthogonal experiments were used to optimize technological conditions for preparing collagen from the body of this brown frog with pepsin. The type of pepsin-solubilized collagen(PSC) was determined by ultraviolet and visible spectrophotometer(UV),and the contents of amino acids in PSC were determined by using reversed phase high performance liquid chromatography(RP-HPLC); ResultsThe optimum technological conditions of PSC were that 37 ℃ for temperature,20% for E/S,1∶20 for the ratio of material to solvent and 12h for time. Under these conditions,the extraction rate of PSC was up to 88.6%. The PSC had the strongest absorption peak at 234 nm through UV analysis.  Results: of RP-HPLC analysis showed that PSC contained abundant of amino acids,especially 8 essential amino acids needed by human body,in which Gly,Pro,Leu and Ala had higher contents than the others,which matched with the features of collagen Ⅰ.  Conclusion:The optimized preparation method had high extraction rate and good repeatability, thus could provide references for technological production of PSC.