Anti-theft cylinder lock

The anti-inserting theftproof spring lock of the utility model relates to a lock, especially to an oblique tongue type spring door lock, the spring lock and the lock groove are provided with anti-inserting theftproof metal pieces, the two anti-inserting theftproof metal pieces are respectively disposed on the outlet edge of the lock tongue inclined plane of the oblique tongue type spring door lock and the inlet edge of the oblique tongue inlet groove inclined plane of the lock groove, the anti-inserting theftproof metal pieces are folded outwards with a certain angle at the above position, the two anti-inserting theftproof metal pieces are anastomosed to be Y-shaped when closing the door; the anti-inserting theftproof metal pieces folded outwards show ladder in shape, the upper and the lower edges are both cutted into inward oblique lines. The arrangement of the anti-inserting theftproof metal pieces can ensure that the oblique tongue inclined plane of the oblique tongue type spring door lock is not affected by outer force, which can prevent that lawbreakers use the inserting piece or hook piece made of various materials to insert in the door or hook the oblique tongue into the room, so that the oblique tongue type spring door lock can prevent the inserting and stealing without locking the insurance, which is convenient for daily work and life of people.