The invention relates to a grain cylinder turning motor including a driving shaft assembly, a front cover assembly, a planetary gear, a gear deceleration shaft, a ring gear, a gear chamber cover, a motor front end cover, a stator assembly, a rotor assembly, a brush holder assembly, and a rear cover, the front cover assembly and the ring gear are connected through a pin shaft, the planetary gear and the gear deceleration shaft are arranged in the ring gear and are axially and alternatively arranged along the ring gear, the gear chamber cover is successively connected with the ring gear and the front cover assembly, the motor front end cover is fixedly connected with the gear chamber cover, the stator assembly and the rotor assembly are arranged in a motor casing, the rotor assembly sleeves the driving shaft assembly, the brush holder assembly is arranged in the rear cover, the right side of the rear cover is provided with a solenoid valve, and a motor casing is provided with a protective controller through a fastener. The solenoid valve coil assembly is turned on 0.5-1s in advance under a chip controller to make a movable iron core move. When the coil assembly is disconnected from power, the movable iron core is reset to lock the motor shaft under the guiding effect of a return spring and a bottom plate.