Abstract: The Upper Cambrian Xiaqiulitage Formation in Tarim Basin has widely developed thick dolomite on restricted platform,and has become the most important reservoir.According to the multidisciplinary analysis of the data on wells and seismic,the Upper Cambrian Xiaqiulitage Formation is divided into four sequence stratigraphic units in Bachu area.The sequence stratigraphic units were charactered by TST and HST.The HST does not develop completely.On the multidisciplinary analysis of lithologic character of dolomite and indication of oil and gas on wells,the sequence stratigraphic units have vital effect on dolomite reservoir.The karstic dolomite reservoir mainly developed in the HST of sequence stratigraphic,especially in the last period of HST with exposition.