The invention discloses a medicinal composition for treating type 2 diabetes of mammal including human, in particular a medicinal composition containing fixed amount of (3aS,5s,6aR)-5-2-((2S,4S))-2-cyan-4-fluor-1-pyrrolidyl)-2-oxy ethyl amino)-N,N,5-trimethyl-hexahydro[C] pyrrole-2(1H)-carbamoyl or pharmaceutically acceptable salts thereof and melbine or pharmaceutically acceptable salts thereof (such as hydrochloride), a method for preparing the medicinal composition and application of the medicinal composition in treating the type 2 diabetes of mammal including human.