Abstract: HV insulators take on an important role in power transmission engineering. Because of the rapid development of industrialization, sandstorms and smog often happen. Contamination particles deposit on insulator surface under air flow field, pollution high voltage flashover accidents are prone occur, which seriously affects the safe operation of the power grid. In this paper, to investigate the mechanism of pollution high voltage flashover, a coupling analysis of dynamic accumulation and electric field distortion on insulator surface is explored. A model of gas-solid two phase flow around insulator is established by Euler-Euler approach to simulate the dynamic pollution accumulation process. Thus the distribution of non-uniform contamination layer on the insulator surface is obtained. The surface conductive layer element of the contamination layer is created, and it is used in finite element model of electric field on the polluted insulator, and the electric potential and electric field of the insulator string with non-uniform contamination are analyzed. The results show that: in the case of non-uniform contamination layer, the circumferential position of the polluted layer on the insulator surface has less influence on the trend of its potential distribution, but has greater influence on the position of electric field distortion. With the variation of circumferential position, the deviation of electric field distortion position is different, and maximum deviation occurs on crosswind. The electric field intensity is larger than clean insulator surface with increase of contamination layer conductivity. Furthermore, the field intensity distortion on leeward is the largest.