Abstract: Based on experiment data,studies on effects of salinity, lithology and physical property of different injected water on dynamic porosity exponent (M) and saturation exponent (N) are performed,and an interpretation model between the dy- namic M and N values and the solution resistivity is estab- lished.After the modification by Archie Equation,the inter- pretation precision of saturation of remaining oil at different waterflooding periods is highly enhanced.