An oil well blowout prevention anti-theft device is provided, wherein, an open slot is provided in the block, the open slot is inserted in the big four-way clamp terminal, and is blocked by the clamp head, the cap suspension is packaged outside the block, the interior diameter of the left end of the suspension cap is smaller than the external diameter of the block, the right end of the suspension cap is provided with inner screw thread, and is connected to the external screw thread of the valve body, the valve body extends in the inner bore of the right end of the suspension cap, a valve ball and a spring is placed in the valve body, the spring base is connected to the left end of the valve body, the left end of the spring is pressed in the spring base, and the right end base of the spring is pressed on the valve ball, the left end of the blooie pipe is in inner screw thread connection to the right end of the valve body, the anti-theft plug is mounted at the right end of the blooie pipe, the pressure release adjusting rod extends in the blooie pipe, the external screw thread on the pressure release adjusting rod is screwed with the inner screw thread on the anti-theft plug, so that the theft can not dismount the valve body by ordinary tools, the gas in the well is unable to outflow under the action of the valve ball, therefore the theft can not take away the gas in the casing tube, the gas in the casing tube increases, after pressurizing, the gas can be discharged by rotating the pressure release adjusting rod to recover the gas.