Abstract: LWD is a logging technology to measure formation information while drilling.It has the following several advantages,such as accurate measurement,high efficiency and low risk.This technology has been used in various kinds of well-type,including vertical well,directional well,highly deviated well and horizontal well.In 2014,COSL researched and developed its own LWD system named Drilog independently.It broke the international monopoly after the application in BoHai oilfield successfully combined with rotary steerable drilling system named Wellleader.In this article,to confirm the stability,consistency and applicability of Drilog system,analysis has been conducted on quality,invasion and geosteering etc.with the application examples in BoHai oilfield.Finally,we got some conclusions and proposed some suggestions.