Abstract: The Buqu dolomite of the Middle Jurassic in Longeni-Angdaercuo area in Tibet is a sequence with petroliferous prospect. To understand its genesis is very significant for accurate evaluation of petroliferous potential in the study area. This paper analyzes the fluid inclusion, carbon and oxygen isotopes in oil-bearing dolomite in this area, showing that the homogenization temperature mainly ranges from 130℃ to 170℃ and the salinity mainly ranges from 3.5% to 4.5% of fluid inclusion in dolomite zones, which indicates that the dolomite zone-formed environment temperature and salinity are all relatively high and they should be the products of deep-burial to late-stage diagenesis. All the δ18OPDB values of dolomite are less than zero (migrating toward negative values) and vary largely, indicating the low-temperature and high-temperature genesis of dolomite. Based on the combination of field survey and indoor test and analysis, it is considered that the dolomite in the study area experienced a complex genesis—at least the compound of 3 stages of genesis, namely low-temperature penecontemporaneous dolomitization at the early stage, high-temperature and deep-burial dolomitization at the middle stage and structural dolomitization at the late stage