In order to prepare high purity tungsten silicide (W-Si) alloy powder, high purity W powder and Si powder as starting materials were pre-alloyed in high temperature and vacuum environment. The pre-alloying temperature was 800, 1000 and 1200 oC, and the optimized temperature was 1000 oC. Through the pre-alloying of 1000 oC, the W phase disappeared and the WSi2 phase formed in the powder. The powder particles present single peak distribution and the particle size of d50 is 21.037 μm, and d90 is 50.905 μm. And the powder purity could reach more than 99.995%. Using the pre-alloying tungsten silicide powder as material, the magnetron sputtering target was sintered with a uniform microstructure and alloy composition, which solve the problem of non-uniform microstructure and alloy composition of tungsten silicide target