The utility model relates to a centrally installed switchgear earthing knife-switch locking device, and belongs to the field of security protection of power equipment. The technical scheme adopted in the application is that the centrally installed switchgear earthing knife-switch locking device comprises a sheet-like lockout body; the upper side of the sheet-like lockout body projects to form a rotating portion; the rotating portion is provided with a screw hole; the lower portion at the right side of the sheet-like lockout body is provided with a keyhole portion perpendicular to the lockout body; the keyhole portion and a centrally installed switchgear keyhole match a padlock nose; the right side of the lockout body is indent; and the upper right of the lockout body forms a catch portion projecting from the rotating portion and the lockout body. The application has the beneficial effects of being capable of achieving complete lockout through addition of the device to a 10kV centrally installed switchgear after the earthing knife-switch is switched on, preventing accidental pulling of the earthing knife-switch, making up for designing flaws of original equipment, avoiding accidental pulling due to the loss of five-prevention after the earthing knife-switch is switched on, ensuring the safety in line maintenance, equipment maintenance personal safety and equipment safety, and improve the reliability of the switching operation.