For a high altitude experiment, the lateral distribution (particle density distribution) of secondary particles at detector level is an important parameter to get the information of primary shower event. During thunderstorms, the charged particles in extensive air showers will be accelerated or decelerated in strong atmospheric electric field. The intensity and the position of ground cosmic rays could be influenced. In this work, Monte Carlo simulations are performed by using CORSIKA to study the effect of thunderstorms electric field on the lateral distribution of charged particles at YBJ (4300 m a. s. l., Tibet, China). We found that the lateral distribution will be changed significantly in thunderstorm field. And the variation amplitude is found to be highly dependent on the electric field, the zenith angle of the primary shower event and the distance to the shower core. Our simulation results could be helpful in understanding the phenomena observed in ground based experiments (such as ARGO-YBJ) and the physical mechanism of secondary charged particles accelerated by thunderstorm electric field.