3D FE model of long air gap and composite laminate was built.Positive streamer growth probability model of along rod-plate gap is a stochastic dischargeone based on the traditional streamer theory. The detailed simulation process includes potential calculation of each grid point in air gap, routes list of all streamer developed around the pole, growth time calculation of route developed for each streamer and route definition with the minimum growth time as the selected priority one. When the streamer reaches composite plate, cross point of the streamer and plate is regarded as the attachment pointof lightning strike. Potential, temperature and heat stress distribution of composite plate can be obtained under high voltage wave of lightningstrike through direct effect analysis. The results show that high potential, temperature and heat stress produced instantaneously by fast streamer mainly spread out symmetrically along direction with the maximum conductivity on top plate. But the study in this paper only provides the preliminary analysis results as a quality description. In order to more accurately simulate the process of composite discharge effect under lightning strike, damage mechanism of ablation and heat mechanics for composite laminate needs to further take into account.