A detailed analysis of the geological logging data from Wells BK2, BK3H, BK4H and BK5H and other 2wells shows that the hydrocarbon showings generally are oil slicks, oil trace, gas gas-log anomaly in rank from the upper to the lower of the Lower Permian Bachu top oil reservoir in Bashituo Field. Quality of hydrocarbon is better in the upper than in the lower. Hydrocarbon is commonly concentrated in the top part of the top reservoir, which implies hydrocarbon migrating upwards and accumulating. Bachu Formation and the layers above it are well stable in vertical and horizontal for no obvious change in depth and thickness, and show a change of regular thickening or thinning alternation in every directions around Well M4 as a center. It is indicated that Bachu reservoir is worthy for exploitation.