Influence of material parameters on quantum efficiency of In_0.53Ga_0.47As photodetector is presented. The results show that the quantum efficiency mainly depends on the direction of incident light, the carrier concentrations of P-region and N-region, and the surface recombination velocities and the thickness of each region. When light is injected from P-side, the surface recombination velocity, carrier concentration and thickness of P-region have significant impact on the quantum efficiency. The material parameters of N-region have slight impact on quantum efficiency. Under condition of high carrier concentration (n>10¹⁷ cm^-3), the surface recombination velocity and thickness are major factors. When light is injected from N-side, the surface recombination velocity of N-region is the major factor of quantum efficiency, if the carrier concentration is less than 10¹⁷ cm^-3; the material thickness is the major factor of quantum efficiency, if the carrier concentration is more than 10cm¹⁶ cm^-3.