There are karst fractured/caverned reservoir formed by multi-phase karstification in Tabei uplift and Tazhong lower uplift of Tarim basin, but large scale karst-cave layer have not yet been found in the Bachu uplift. The Yingshan Formation in Xianbazha 3D area of the western Bachu denudation area is directly covered by the Silurian formation. During the middle-Caledonian, the Yingshan Formation exposed to surface for a long time and developed karst cave after atmospheric water eluviation. The branch-like river was mature and had steady valley, which indicates a good lithologic-structural condition and abundant atmospheric fresh water in this area.Therefore, the surface karst is quite developed; drainage for the subterranean rivers, which had a few branches, was mainly controlled by the distribution of the trunk of surface rivers and scattered depressions. It is suggested that the subterranean rivers did not form a system of hydrologic groundwater network, so that underground karst development is confined. Based on analyses of karst characteristics in this area and analog study of karst in Xikeer outcrop, the reasons for the low level of underground karst development were sum? marized as follows:①incomplete karst development; ②cavern filling ; ③layers having developed solution pore and cave .