With the progress of oil exploration and development technology, rotary steerable drilling system is more and more applied in modern drilling. But when faced with more complex and higher curvature wellbore structure, the drilling operation requirements can not be fully met only by Xceed rotary steerable tools. In view of this situation, a special PDC bit with gauge structure was put forward, whose special lies in 1in standard gage in upper gage and 3in in lower gage with 0.6 degree taper. The computer simulation analysis shows that this PDC bit can not only improve the ability of BHA whipstocking, but also improve the drilling tool operation stability compared with conventional PDC bit. The field application in Bohai oilfield indicates the stronger whipstocking capacity of this PDC bit with special gauge structure to ensure the stability of rotary steerable tool and other downhole tools and slow down the downhole instrument failure caused by underground vibration.