The invention relates to a lock cylinder automatic machining device which comprises a first machine frame and a second machine frame, wherein a vibration material disc is arranged on the first machine frame, a rotation disc component is arranged on the second machine frame, a plurality of sets of locating dies are arranged in the circumferential direction of the rotation disc component and located on the second machine frame. The periphery of the rotation disc component is provided with a feeding unit, a drilling unit, a first groove milling unit, a second groove milling unit, a third groove milling unit, a first oblique hole machining unit, a second oblique hole machining unit and a discharging unit in the anticlockwise direction. A discharging pipe of the vibration material disc extends into the feeding unit, and the first machine frame is further provided with a locating unit. The lock cylinder automatic machining device has the advantages that the structure is simple, operation is simple and convenient, whole automation of the lock cylinder machining is achieved through all units, machining efficiency is good, quality is high, time and labor are saved, investment on enterprise labor resources is saved, production efficiency is greatly improved, and whole-journey automation of lock cylinder machining is achieved.