Abstract: The fine description of thin layer, sedimentary subfacies and microfacies analyses and reservoir prediction have been made in thin sand body in the Halahatang Formation of the Upper Triassic in the Tahe Oil Field. The range and rule of sand body distribution have been concluded. Based on previous actual drilling data, the fine interpretation of structure has been made combined with seismic analysis. Through core sample observation, analysis and well logging evaluation, combined with dynamic and static data from producing well, the traps in target layers have been evaluated. Favorable traps have been pointed out and reserves have been calculated. Some old wells have been reviewed. The petroleum-bearing capacity of sand body has been judged, providing basement for the further exploration of old wells.