The invention relates to a bus grounding knife-switch interlocker. The bus grounding knife-switch interlocker comprises two locking plates, a crescent plate, adjusting bolts, a pull rod and a locking groove, wherein the two locking plates are arranged on bus knife-switch movable contact arm bases at two sides respectively; two ends of the pull rod are connected with the crescent plate and the locking groove through the adjusting bolts respectively; and the other side of the crescent plate is fixed on a transverse rotating connecting rod of a grounding knife-switch. Based on the original knife-switch design, the effective mechanical locking of a double-bus grounding device in a locking state on bus isolating switches at two sides can be thoroughly realized, accidents of mistakenly switching on the bus isolating switches and the bus grounding knife-switch are eliminated, and the interlocker has a high safety coefficient and a strong defense function.