Theft-proof lock with defensive lock pin

A theftproof lock with defensive lock core includes a lockset body, a locking tongue, a connecting rod, a lock casing and a lock core, a defensive lock core is provided on the front end of the original main lock core, the front and the back of the two lock cores close to and independent with each other, the main lock core on the back end connects to the connecting rod and the locking tongue in turn. The theftproof lock extends into lock from the front lock core (defensive lock core) only by a special key to open the lock, when using other non-key tools, because the defensive lock core is blocked, without rotating the main lock core, thereby improving safety performance of the theftproof lock. The utility model is adapted for various theftproof lockset.