Gear is a widely used common part of machinery, which is of good lubricate property and low materials consumption when it is made of sinter powder material. In this paper, the chemical composition, microstructure and property of sintered gear were investigated with optical microscope, scan electronic microscope, micro hardness meter and X-diffraction energy spectrometer. The results show that the microstructure of the gear includes of tempered martensite, carbide, residual austenite and a small quantity of cavity. The distribution of iron element is even. The copper and nickel distribute unevenly and cover around the surface of carbide in gear material which makes different property of covered layer itself between carbide and base material. The existing of covered layer and weak grain-boundary strength are main reason for gear brittle fracture. The gear’s toughness can be increased by optimizing sintering technology and heat treatment.