Abstract: Yaha Oilfield is the most hydrocarbon province in Tarim Basin,which widely developed the condensates in the Triassic reservoir.Geochemical analysis illustrates that the condensate oil is low mature with Ronear 0.7%,which reflects the characteristic of the subsequent condensates.Moreover,the changing tendency of the light component describes a obvious figure of phase fractionation that controls the generation of the condensates.The phase characteristics of the condensates can be clarified into two types:first is the saturated condensates that have a small difference between the FMP and DPP,which mainly develop around the YH7 well;another is the unsaturated reservoir that have a large difference between the FMP and DPP,which develop in the YH3 well and YH6 well area.The generation of the secondary condensates is controlled by the multiple episode of the hydrocarbon charging.Slight amount of the oil charged the YH1 and YH5 well without YH3 well area in the early episode.Moreover,great quantity of dry gas invaded the YH1 well and YH7 well area,which turned YH3 well area into unsaturated condensate by both the change of temperature and pressure and the light component migrated by dry gas.