Abstract: By using the data of drilling coring, fluid testing, production capacity testing and chemical analysis, the reservoir characteristics of the lower member of Minghuazhen formation in the Huanghekou sag were comprehensively evaluated. Based on the parameter analysis of petrology, physical property, reservoir interstitial material and micro pore structure, the classification criteria of different types of reservoirs were established, and the characteristics of different types of reservoirs and their relationship with productivity were determined. The results show that the reservoirs in the lower part of the Minghuazhen formation in the Huanghekou sag can be divided into three types, and type I and II reservoirs control the distribution of the oil-bearing favorable areas. The reservoir production capacity and the fluidity have a high correlation. When the fluid properties are similar, the better the particle sorting of sandstone reservoir, the larger the pore throat radius, the more uniform the pore throat structure, the higher the fluidity, the higher the oil production index, and the higher the production capacity.