To analyze effects of injectors on characteristics of supersonic combustor with staggered rear strut and cavity, numerical simulation was carried out to investigate influence of different injection positions for single and multiple injectors on mixing efficiency of fuel.At last, the effects of the injectors on flow filed with different injection angles were explored.The findings of the study are as follows, the injector which facing directly to the declivity of the strut has better effect on spreading of fuel and mixing efficiency, the conclusion also applies to multiple injectors.With injection angle approaching 90°, the penetration depth and distance of the fuel increase.With increasing of injection angle, total pressure loss also increases.