Abstract: In order to investigate the change law of electric field distortion region around buildings in thunderstorm, the effect of thunder cloud and building structure on the electric field distortion region around the buildings was simulated by IES (electromagnetic transient simulation software). The results showed that lightning stroke probability could be reduced for group buildings in thunderstorm, because of the shield effect which changed the degree of electric field distortion around the buildings, and reduced the probability of upward leader and lightning stroke in thunderstorm. For single building, the area of electric field distortion was a hemisphere and there was a linear correlation between the degree of electric field distortion and the height of the building. The higher the building was, the greater the distortion region would be. That could lead to a greater extended region of the front discharge, and the probability of upward leader could also be increased, which was the reason for higher objects to be easily stroked by lightning.