绝缘介质表面流注发展过程是沿面闪络中最为重要的物理过程。利用紫外仪拍摄了空气中和不同绝缘介质表面流注传播路径，发现绝缘介质表面流注拥有‘沿面’路径和‘空气’路径两个路径。带伞裙的绝缘子表面流注“沿面分量”不能越过伞裙传播到达上极板，只有“空气分量”可以到达上极板。通过提高平板间所加电压，研究了空气间隙和绝缘子闪络特性，分析了流注稳定传播场强和50%闪络电压的关系。利用照相机拍摄了光滑绝缘子和不同伞裙结构下绝缘子沿面闪络的路径，将流注发展路径和沿面闪络路径进行对比，建立了光滑绝缘子及不同伞裙结构绝缘子表面流注路径和沿面闪络路径之间的关联。“,”The streamer is the most critical and complex stage of the electrical breakdown, and is important in the determination of electrical breakdown characteristics of the electrode gap. The photographs, showed the path of the streamer propagation in air alone and along the smooth cylindrical insulator or insulator with shed, were taken by ultraviolet camera. The streamer propagated along smooth insulation surface with two propagation paths. That is‘surface’ component propagating along the insulation surface and ‘air’ component propagating in air. As a shed appeared on the insulation surface, the ‘surface’ propagation path was cut off, hence, the ‘surface’ component of streamer never reached the cathode. The ‘air’ propagation path could bypass the barrier, and the ‘air’ component of streamer would cross the gap to reach the cathode. Through improving the applied voltage between the plates, the characteristics of flashover in air gap and along the insulation surface were investigated deeply. The relations between the streamer‘stability’ propagation fields and the 50%breakdown voltage were analyzed. The flashover path along the insulators with a shed was shot by a camera, which was compared with streamer propagation path. Hence, the relation between streamer propagation path and the flashover path along the insulators with a shed was found.