Abstract: The division of oil and gas accumulation periods is of great significance for revealing the occurrence laws of hydrocarbon and guiding exploration and development. By measuring the homogeneous temperature of fluid inclusions in the Shanxi-Shihezi Formation in the Wuqi area of the Ordos Basin, combined with petrological characteristics and thermal evolution history research methods, the timing of oil and gas charging can be determined. The results show that there are mainly two stages of fluid inclusions in the Shanxi-Shihezi formation in study area, the early inclusions are mainly distributed in the microcracks inside quartz particles, and the late inclusions are mainly distributed through microcracks or the quartz secondary enlargement, and a small amount of them can be found in the late cement. Through homogenization temperature test, the peak temperature distribution of early inclusions is 110℃~120℃, and the peak temperature distribution of late inclusions is 140℃~150℃. Combined with the analysis of the thermal evolution history and diagenesis, it can be concluded that there are two periods of oil and gas filling: the first period of oil and gas charging time is the Late Triassic-Early Jurassic (212Ma~195Ma), the reservoir is in the middle diagenetic stage A. During this period, the thermal evolution of the coal bearing stratum reaches the mature stage, and dissolution and replacement are main process; the second period of oil and gas charging time in the Late Jurassic-Early Cretaceous (155Ma~130Ma), the reservoir is in the middle diagenetic stage B, and diagenetic process is mainly dominated by dissolution of calcareous cement, which increases the secondary pores and reaches the highest thermal evolution, which is the main charging time.