Abstract: Xiaerpu granite is one of the typical magma mixing granites in West Junggar,which is composed of the host rock,mafic microgranular enclave,and basic dyke swarm.The double diffusion and relativity of geochemistry are one of the most effective means of differentiating magma mixing.Petrochemistry features are difference between the host rock and basic dyke swarm which have distinct evolution.There was strong double diffusion between the host rock and mafic microgranular enclave,and affinity between mafic microgranular enclave and basic dyke swarm.Xiaerpu granite is the mixture between mantle magma represented by mafic microgranular enclave and basic dyke swarm and crust magma represented by the host rock.Magma mixing information from geochemistry is in conformity with petrographical feature,which support magma mixing,providing an important proof for solving the difference of Xiaerpu granite's origin from petrographical field.