Abstract: Geosteering drilling technology is one of the most advanced drilling techniques in late years.Navigational drilling can control well trajectory according to the actual geologic features surveyed by LWD.Based on theoretical research,SDRI(Shengli Drilling Technology Research Institute) had developed with its own effort new types of positive pulse MWD tool,gamma ray while drilling tool and resistivity while drilling tool,and developed geosteering drilling software.Shengli Oilfield had achieved its LWD design and manufacture technique and geosteering drilling technology.The geosteering drilling system had been used in 30 horizontal wells,94.36% of the horizontal sections penetrated within reservoir,and the thinnest reservoir is 1 meter.Geosteering horizontal drilling technology provides a key solution for the development of thin reservoir and the left oil in the upper section of thick reservoir.