The invention discloses an anti-theft lock safety protection device. An anti-theft lock comprises a shell and a key cylinder. The key cylinder comprises an inner cylinder body and an outer cylinder body. The anti-theft lock safety protection device is arranged in the shell. The anti-theft lock safety protection device comprises a groove type photoelectric switch and an acoustic alarm circuit. An outer cylinder body connecting piece which extends to the side face of the outer cylinder body is arranged on the end face of the end, facing the inner cylinder body, of the outer cylinder body. A stopdog located on the side face of the outer cylinder body is arranged on the outer cylinder body connecting piece. An inner cylinder body connecting piece which extends to the side face of the inner cylinder body is arranged on the end face of the end, facing the outer cylinder body, of the inner cylinder body. The inner cylinder body connecting piece and the outer cylinder body connecting piece are the same in extension direction. The groove type photoelectric switch is arranged on the inner cylinder body connecting piece. The stop dog is located in a groove of the groove type photoelectric switch. The acoustic alarm circuit is connected with an output end of the groove type photoelectric switch. The invention further discloses a safety alarm method of the anti-theft lock safety protectiondevice. The anti-theft lock safety protection device and the safety alarm method of the anti-theft lock safety protection device are novel and reasonable in design, high in universality, capable of effectively preventing a thief from unlocking, capable of greatly improving the anti-theft efficiency of the anti-theft lock, high in practicability and convenient for promotion for use.