The invention discloses an anti-theft lock cylinder with an alarm triggering function. The anti-theft lock cylinder with the alarm triggering function comprises a lock cylinder shell, a lock cylinder body, a snap ring, a bayonet pin, a gland, a locking piece, a triggering switch and an ejector pin. The front end of the lock cylinder body is sleeved with the snap ring. The front end of the snap ring is provided with a first clamp groove. The side wall of the snap ring is provided with two second clamp grooves and a snap ring through hole. The lock cylinder shell is provided with a lock cylinder shell hole. The lock cylinder body is provided with a lock cylinder body hole. The bayonet pin comprise a first pin rod, a second pin rod and a third pin rod, wherein the first pin rod is arranged in the lock cylinder body hole, one end of the second pin rod is arranged in the lock cylinder body hole, the other end of the second pin rod is arranged in the snap ring through hole, one end of the third pin rod is arranged in the snap ring through hole, and the other end of the third pin rod is arranged in the lock cylinder shell hole through a spring. The gland is arranged at the front end of the snap ring in a covering manner and provided with a locking hole. The front portion of the locking piece is arranged in the locking hole through a spring, and the back portion of the locking piece abuts against the inner portion of the first clamp groove. The triggering switch is arranged on the lock cylinder shell. One end of the ejector pin abuts against the side wall of the snap ring, and the other end of the ejector pin abuts against a contact point of the triggering switch. The anti-theft lock cylinder with the alarm triggering function is high in anti-theft sensitivity, easy to operate and suitable for stopping locking under the condition of violent lock picking.