There were different opinions about the origin of petroleum property variations in the Lunnan Low Uplift of the Tarim Basin. In this paper, a software PVTsim was applied to investigate the compositions of the petroleum fluid inclusions in different sets of reservoir rocks from this area. The results show that there are three phases of petroleum inclusions in the Ordovician carbonate reservoirs and two types of petroleum inclusions in the Carboniferous and Tri-assic sandstone reservoirs. The three phases of the petroleum inclusions from the Ordovician reservoir rocks have similar compositions with the type 1 petroleum inclusion from the carboniferous and Triassic reservoir rocks, but the type 2 petroleum inclusion from the carboniferous and Triassic reservoirs is characterized by higher content of C1 and higher GOR values. With the combination of the geological background, it was inferred that the current petroleum pools in the Lunnan Low Uplift were formed mainly by two phases of petroleum charges, one i There were different opinions about the origin of petroleum property variations in the Lunnan Low Uplift of the Tarim Basin. In this paper, a software PVTsim was applied to investigate the compositions of the petroleum fluid inclusions in different sets of reservoir rocks from this area. results show that there are three phases of petroleum inclusions in the Ordovician carbonate reservoirs and two types of petroleum inclusions in the Carboniferous and Tri-assic sandstone reservoirs. The three phases of the petroleum inclusions from the Ordovician reservoir rocks have similar compositions with the type 1 petroleum inclusion from the carboniferous and triassic reservoir rocks, but the type 2 petroleum inclusion from the carboniferous and triassic reservoirs is characterized by higher content of C1 and higher GOR values. With the combination of the geological background, it was inferred that the current petroleum pools in the Lunnan Low Uplift were formed mainly by two phases of petro leum charges, one i