Abstract: The photoelectric properties of the infrared detector will be affected by the multiplier layer parameters of the internal structure. In order to improve the avalanche effect of the device, the effect of residual doping concentration and thickness of type I multiplier layer on the performance of InSb-APD infrared detector with heterogeneous SAM structure was investigated in detail with the simulation software Silvaco-TCAD. The results show that as the doping concentration of type I multiplier layer increases, the peak electric field intensity within its multiplier layer increases, and the optical responsivity increases slightly. The increase of the thickness of type I multiplier layer rises the optical responsivity and dark current density of its multiplier layer, and the peak electric field intensity decreases. Further studies show that the avalanche process is favored when the residual doping concentration and thickness of the type I multiplier layer are 1×10¹⁵ cm⁻³ and 3 μm, respectively.