Polluted insulators frequently face flashover accident and it threatens the safety and stability of power system. In order to help to reduce the occurrence of flashover, it is necessary to study the contamination characteristics of insulators and its influence factors. In this study, the contamination of insulator is simulated by the Eulerian multiphase model in computational fluid dynamics. The flow field around insulators is calculated and the volume fraction of the particle phase is used to characterise the pollution degree on insulator surface. Results show that the pollution is mainly distributed on windward side and leeward side of insulator. The crosswind side of insulator is slightly contaminated. The four influence factors, wind velocity, particle concentration, particle diameter and flow angle have different effects on insulator contamination. Among these factors the particle concentration contributes most to the whole contamination degree of insulators. A wind tunnel contamination test on insulator is carried out to verify the feasibility of the numerical simulation. It can be found that simulated contamination distribution and variation of contamination degree with wind velocity well coincide with the results of wind tunnel test. The numerical simulation in this study is practical in studying the insulator contamination.