A valve safety mechanical interlock device for high voltage switchgears consists of a high voltage switchgear cabinet body and a high voltage switch arranged therein, a vacuum circuit breaker and a current transformer. The high voltage switch and the current transformer thereof are provided in the cabinet body, the vacuum circuit breaker is arranged on a switch car, the switch car is mechanically interlocked with a valve by a push rod and a valve crank arm, a slide block is provided on the switch car frame. A support is fixed on the cabinet body, the support is arranged with a slide bar which is corresponding to the slide block#GB001s position on the switch car and a lock pin integrally connected with the slide bar. An elastic element is provided on one side of the slide bar, a lock ring is connected with the lower part of the valve crank arm, a keyhole is arranged on the lower part of the lock ring at a position which is corresponding to the lock pin. The utility model has a simple structure and a reliable performance. The locking and unlocking are spontaneously realized during the course of the switch car#GB001s moving in and out of the cabinet body, the mechanical interlock of an active protection door and the switch car can be ensured.