Abstract: Fluid inclusion has important application in reservoir geochemistry. GOI (grain with oil inclusion) value, the homogeniation temperature and MCI (molecular composition of inclusion) can be used to determine the paleo-OWC (oil water contacts), the charging time and hydrocarbon charge history respectively. Freezing point can describe the evolution of strata water and the oil reserves. Besides, fluid inclusion also can be used to determine the evolution stage of reservoir, migration orientation, and abnormal pressure of basin. Some problems and research trend are also discussed.