Abstract: In recent years, the waterflood development of Honghe oilfield was characterized by low porosity, low permeability, extra-low permeability, poor water injection and low recovery degree. Therefore, it is necessary to make further consideration on the original oil saturation and hydrocarbon microcosmic enrichment regularity. Through the analysis of mercury, phase permeability and nuclear magnetic resonance(NMR), the discussion on oil content and oil saturation range of Chang 9 reservoir was carried out. The comprehensive comparison indicated the reservoir was controlled by material and unsaturated oil and gas. Considering the explanation of the dynamic water saturation and the production water of the nuclear magnetic logging, the original oil saturation value of the reservoir was determined between 25% and 45%.