The utility model discloses a grounding insulator with a lightning protection function, which comprises a shell, a plurality of zinc oxide valve pieces and electrodes, wherein the top end of the shell is connected with an electrified body, the tail end of the shell is grounded, the electrodes are arranged at the top end and the tail end of the shell respectively, the plurality of zinc oxide valve pieces are arranged in the shell at intervals, and the electrodes and the zinc oxide valve pieces are electrically communicated. Through the zinc oxide valve pieces which are arranged at intervals, lightning energy is discharged by using nonlinear volt-ampere characteristics of the plurality of zinc oxide valve pieces, thereby realizing lightning protection. The grounding insulator operates reliably under various conditions of system voltage, transient overvoltage, operating overvoltage and the like, and lightning current can be discharged reliably when a grounding wire is struck by lightning in particular, thereby ensuring the safety of line equipment. In addition, the grounding insulator can be reliably matched with grounding wire broadband carrier equipment, thereby ensuring that multiple sets of equipment can operate safely. The grounding insulator can also withstand the loaded DC voltage for a long time during DC deicing of the grounding wire.