Anti-theft device for producing well head casing

The utility model relates to an anti-theft device for a producing well head casing, which comprises an anti-theft valve and a test blow-down joint, wherein the anti-theft valve is provided with a connecting sleeve; a check valve and a connecting check ring are arranged in the connecting sleeve; the check valve comprises a valve body, a valve core and a guide seat; the center of the valve body is provided with a step through hole and a tool slot for disassembly and assembly; the guide seat is arranged in the step through hole in a penetrating way; one end of the step through hole is provided with an anti-theft plug through a thread; the outer end of the anti-theft plug is provided with an eccentric annular groove; the valve core is connected with the guide seat in a penetrating way and is capable of axially and freely moving. The anti-theft device has to be disassembled and assembled or opened and closed by using a special tool, and therefore, crude oil of ground pipelines can be effectively prevented from bei