Abstract: Comparative approach was applied to Rana pleuraden (♂16,♀14) and R.chaochiaoensis (♂17,♀17) collected from Aug.1997 to Sept.2000.Their external morphology,muscle and osteological characters were observed and compared.It is expected to find the clues that two sympatric species in the same genus diverge in morphology.The results show that there is different skin color pattern between two species;the squamosal of R.pleuraden is more developed than R.chaochiaoensis;adult male of R.pleuraden is with vocal sac and R.chaochiaoensis without it;there are notable differences in musculus triceps brachii,musculus triceps femoris and musculus tibialis between two species;skeletons of R.chaochiaoensis in limbs are longer and thinner than R.chaochiaoensis and its tuber ischiadicum and acetabulum of pelvic girdle are stronger as well;enlarged bones in braincase are different between two species;musculus rectus abdminis of R.pleuraden is with 4 inscription and R.chaochiaoensis with 5,and so on.Morphologic differences between two frogs are consistent and suitable with their habitat and their living manner.