Proper wellbore pressure management is a critical part of the drilling practice, where static and dynamic fluid pressures are used to contain formation pressures and assure wellbore stability, to solve the problem; the anti-flushing device is has been developed. The anti-flushing device is designed to counter downhole pressure increase due to safety of narrow mud window and the key to fast drilling. Reasonable control anti-flushing device is the best way to solve the safety of narrow mud window and the key to fast drilling. This paper describes the anti-flushing device, which is run as an integral part of the drill string. The anti-flushing device has been built to operate the 8-1/2 "section of well drilling, keeping continuous loop, To avoiding annular cutting is sank into accumulation when the drill string were connected and the pump stopped, cleaning the small hole by maximum.