Accidents of pollution flashover still exists in certain areas. It is still of practical significance to further study external insulation pollution issues. The field observations have already shown that insulator surface is coated with obvious non-uniform pollution on windward and leeward sides. Lack of systematical research on this phenomenon makes the existing contamination tests and outdoor pollution insulation designs not to fully reflect the actual situations. Consequently

by carrying out fluid dynamic simulation and artificial tests

we studied the pollution distribution performance of the windward/leeward sides of insulator and their influential rule on DC pollution flashover voltage. Research results indicate that the contamination on insulator windward/leeward side is in fan-shape non-uniform distribution

and the non-uniformity may reach 1/10. The function of DC electric field

the increment of wind velocity

and particle diameters will enhance the pollution non-uniformity. Under windward/leeward side non-uniform pollution

insulator flashover voltage will subject to a considerable reduction of about 30%. The research results are of certain reference value for the external insulation design of high voltage transmission lines.