Abstract: Contact net insulators as insulation components are of great significance for the normal operation of railway traction power supply systems. When the electric field distribution on the surface of the insulator changes, it will affect the flashover characteristics of the insulator, which will cause the railway locomotive to fail to operate normally. How to obtain the electric field distribution along the insulator is of great important to prevent the insulator flashover and ensure the normal operation of the railway locomotive. After analyzing the factors affecting the flashover of the insulator, the measurement and calculation methods of the electric field along the insulator surface of catenary are introduced. The advantages and disadvantages of different methods are analyzed. It is pointed out that the finite element analysis method will be the main method to study, design and optimize the electric filed distribution along the surface of catenary insulators in the future.