Anti-theft opening device for wellhead valve of oil field

The utility model discloses an oil field well mouth valve anti-theft opening device which comprises an outer sleeve and an adapter, the outer sleeve is in a cylinder shape, the outer sleeve is rotatably arranged outside the adapter in a sleeved mode, and a protective cap is rotatably arranged on the upper portion of the outer sleeve. More than two locking blocks used for locking and positioning the protective cap in the axial direction of the outer sleeve are arranged between the protective cap and the outer sleeve, when each locking block rotates to a certain angle, the protective cap and the outer sleeve are unlocked, so that the protective cap can move and be taken down in the axial direction of the outer sleeve, and axial locking between the protective cap and the outer sleeve is achieved through the locking blocks; and the valve can be opened only under the condition that the password of each locking block and a special opening tool are known, so that the anti-theft function of the valve is greatly impro