Abstract: In this paper,based on the subthreshold current and surface potential model,setting up the structure and physics model of short-channel n-MOSFET by using commercial simulation software,the subthreshold current of device are simulated via 2-D numerical simulation.The channel doping concentration、oxide thickness of gate and the length of channel dependence of the subthreshold current are calculated,the simulation results are investigated through theoretical anglicizing,good agreement is obtained between the calculated model and the simulated results.