Abstract: According to analysis of formation water and crude oil at the west Jinganpu of Damintun Sag in the Liaohe Basin,type NaHCO₃ formation water on the top of the burial hills in the studied area is dominative,type CaCl₂ appear in local area.The result reflects that environment on the top of the burial hills is open and water can alternate in this environment,but it is closed in local area.This enclosed environment is the result of close faults and overlying undercompacting mudstone.Mineralization degree of formation water has the trend that value increase from west to east and the lowest value in west is only(1500mg/L),but in east the value is amount to 9 378.69 mg/L.The zone that presents high degree of mineralization is favorable area that gathers hydrocarbon.Physical property and geochemistry feature of crude oil indicate that migration length of hydrocarbon is short.But in this short distance,the crude property takes place great change.The changes of geochemistry feature show the hydrocarbon migration direction and gathering location.