The invention provides a lock hole cover, which comprises a bottom shell, a top cover, a motor, a motor gear, a fan-shaped gear and a hat-shaped sealing piece, wherein the bottom shell and the top cover are fixedly arranged to form a box body cavity at the interior; and after the lock hole cover is totally closed, an upper column of the hat-shaped sealing piece is sleeved in a lock hole, the bottom surface of a lower column is contacted with the upper plane of the fan-shaped gear, and the bottom surface of the fan-shaped gear is contacted with the bottom shell. The lock hole cover is sleeved on a lock neck to form a whole, and the whole structure as overlapped iron sheets is difficultly broken down; and in a closed state, the hat-shaped sealing piece is sleeved in the lock hole, namely 360-degree stress insurance so as to fulfill the theft-proof purpose. The lock hole cover has the advantages of simple structure, low manufacturing cost, easy operation and practicability, and can ensure that the locks are safer and theft-proof when being arranged on various locks with lock holes.