We have calculated electron energy loss spectrum for electrons transmitted through a mask in projection electron lithography by Monte Carlo simulation based on the dielectric function model and Mott elastic scattering cross section. A good agreement between simulation and experiment is obtained. 利用基于Mott散射截面和介电函数模型的MonteCarlo方法模拟了电子穿透掩膜的能量损失分布,其计算结果与实验结果符合很好。