The invention provides a structure for preventing falling-off of drainage leads. The structure for preventing the falling-off of the drainage leads comprises a grounding knife-switch, the drainage leads, a fixed frame, and a strain insulator and a suspension insulator mounted on the fixed frame, wherein the drainage leads are connected with the strain insulator and the suspension insulator respectively, and pulling cables for preventing the falling-off of the drainage leads are arranged among the drainage leads connected with the strain insulator and the suspension insulator. By adopting the structure provided by the invention, the situation of a short-circuit trip and the like caused by the falling-off of the drainage leads can be prevented, so that the structure can be implemented under the condition of no power interruption, and can be kept in normal operation under the condition that the drainage leads are separated from the insulators to avoid forced stoppage of power supply lines, so as to improve the power supply reliability. The invention further provides an insulating rope with a moisture-proof layer used as the pulling cable, so that the structure further can be operated normally in complex rain and snow weather.