HgCdTe e-APD has been used to detect weak signals. Material growth technique,device process technique and structure design are important for the performance of HgCdTe e-APD.The dark current,avalanche gain and quantum efficiency of a short wave planar PIN device are simulated by silvaco software. The results show that:1)band-to-band tunneling current is the dominated dark current component；2)trap levels that are near the center of the energy gap are the major source of dark current at middle voltage;3)band-to-band tunneling and Impact ionization occur in the light doping avalanche zone;4)at a certain voltage,the dark current and avalanche gain decrease when the width of avalanche gain zone is narrowed;5)at a certain voltage,the avalanche gain increases slightly due to the increase of width of the absorb film,meanwhile the quantum efficiency decreases. Short-wave HgCdTe e-APD with high performace can be achieved under well design of device structure,material growth technique and device process technique.