The invention discloses a locking device for a breechblock of a DF 37-mm anti-aircraft gun. The locking device is fixed on a cradle shell of the original gun, and is provided with a locking rod capable of entering the inner side of the cradle shell in a stretching and retracting mode and stopping a protruding shaft from moving; and a lock plug driven by a motor assembly is driven by a restoring part II to slide against the locking rod, the locking rod penetrates through the locking device and a restoring part I applies restoring force to the locking rod, and the lock plug is used for blockingthe locking rod to restore, so that the locking rod locks the breechblock. The invention further relates to a control method of the locking device for the breechblock of the DF 37-mm anti-aircraft gun. The locking device is simple in structure, low in cost, convenient to maintain and repair and capable of recording information of operators.