Based on drill core and thin section observation, major geochemical element analysis and conventional well log analysis, this study summarizes the characteristics and thickness of weathering crust of Pennsylvanian volcanic rocks (Carboniferous) in Shixi area, Junggar Basin. The weathering crust is identified and divided into three types according to the petrological characteristics and well log interpretations in Shixi area, and the isopach of weathering crust is mapped. The results show that: (1) With the increase of depth, the weathering weakens, and the rocks become less fractured with decreased porosity; (2) the weathering crust of the Upper Carboniferous volcanic rocks can be divided into strongly weathered and mildly weathered layers in Shixi area; (3) the weathering crust is relatively thicker in Dinan uplift and Shixi uplift. This study provides research basis for further evaluation of Upper Carboniferous volcanic reservoir, and will benefit for well location deployment and potential oilfield development in the Shixi area.