In this article we present a Monte Carlo simulation based method to calculate electron beam dose distribution in radiotherapy

for MC method is good at solving particles tranport issue.A MC code

LISTMC

has been developed based on EGS4 and PENELOPE to accomplish the task.In dealing with the inhomogeneous tissue and the complex geometry of human body

its results are more accurate than the methods used in practice.To reduce the lengthy computation time we used some techniques

such as reducing the limitation of boundary of voxel to the path of electron and code optimization etc.In many cases a good coincidence has been observed between EGS4 and LISTMC

but the computation time of LISTMC for 6 MeV electron beams is only 1/10 of EGS4-PRESTA.