The invention discloses a lock hole protection device of a power system. The protection device comprises a cover body, a limiting pin, a spring and the like. The device can be mounted in a lock body without screw fixing and can rotate around a lock cylinder so as to protect a lock cylinder hole; the protection device is provided with a limiting mechanism in the direction covering the lock cylinder hole; and it is ensured that the protection device and a lock are consistent in direction. The lock hole protection device is simple in structure and convenient to mount and apply; the lock cylinder hole is well protected, and influences of climbing of worms, spiders and the like on the lock are avoided; and the service life of the lock is prolonged, normal locking of the lock is ensured, and the normal operation of power system equipment is ensured.