Oil casing coupling structure

The invention belongs to the technical field of petroleum casing pipes, and particularly relates to a petroleum casing pipe coupling structure which comprises a connecting pipe, a thick casing pipe and a thin casing pipe, the connecting pipe is connected between the thick casing pipe and the thin casing pipe, the connecting pipe is sleeved with a fastening sleeve, the fastening sleeve comprises a body, a handheld part and a locking part, and the handheld part and the locking part are formed on the two sides of the body. And an automatic locking part for positioning the thick sleeve is mounted at the locking part of the body. The fastening sleeve is arranged between the connecting pipe and the thick sleeve, when the fastening sleeve rotates, the locking rod slides along the arc-shaped cutting groove of the thick sleeve and then enters the locking hole, meanwhile, the thread structure is arranged between the fastening sleeve and the connecting pipe, firm locking can be achieved under the condition that the rota