The invention provides a pollution flashover test method for simulating erosion and ageing of an RTV coating on an insulator surface. The pollution flashover test method comprises the steps that firstly, a flexible thermal insulation material is used for completely wrapping an insulator coated with the RTV coating, a strip-shaped area is chosen on the outer surface of the flexible thermal insulation material, the flexible thermal insulation material in the strip-shaped area is removed through a cutter and a simulated erosion and ageing belt on the outer surface of the RTV coating is exposed, the RTV coating surface of the simulated erosion and ageing belt is then burned by using a high temperature spraying gun, and at last a pollution withstand pressure test is carried out on the insulator. According to the pollution flashover test method, the pollution flashover resistance level and the service life of the insulator are judged simply, quickly and accurately, the high temperature of aleakage electric current, surface discharge and a flashover electric arc, and RTV coating carbonization caused by the action of a large current and even a melted pollution flashover test can be further simulated, so that the insulator reaching the life time limitation can be changed timely, and the occurrence of a flashover situation is prevented.