Abstract: To develop the evaluation methods of lightning protection system, the high resolution simulation of cloud-to-ground lightning leaders was done based on a 3-D dielectric breakdown model (DBM) in an analytic thunderstorm model, then an evaluation model was established near ground and the evaluation experiment was done. The space resolution is 50 m and the evaluation area resolution is 1 m in the experiment, which could satisfy modeling definition. Using successive overrelaxation method to solve the 3-D DBM, the trace of cloud-to-ground step lightning leaders and potential distribution in space could be gotten. When step lightning leaders arrive at the boundary of evaluation area, 2-D cubic spline method is used to transform the resolution between space and evaluation area. When leader tips a