The utility model belongs to a cover installation and compact structure of locking theftproof, it is at least including casing (1) and installation base (2), casing (1) is connected as an organic wholely with installation base (2), installation base (2) have hole (3) on the installation base about running through, the cover compresses tightly double -screw bolt (4) and passes hole (3) on the installation base, it is articulated with the cover that the cover compresses tightly double -screw bolt (4) one end, the other end that the cover compressed tightly double -screw bolt (4) is the helicitic texture, its thread end passes hole (3) on the installation base, double -screw bolt lock nut (5) and gland nut (6) compress tightly double -screw bolt (4) threaded connection with the cover. The cover need not lifted off to this kind of cover installation and compact structure of locking theftproof just can adjust the degree of compressing tightly, can prevent simultaneously to be protected the problem that became invalid even because of threaded connection takes off the seal failure who leads to soon.