Abstract: The micropore structure of the reservoir of Dengying formation in Gaoshiti—Moxi area of central Sichuan basin is complicated. Weak study on movable fluid is the key factor constraining further EOR in the area. Using analysis means such as cast thin section, SEM, high pressure mercury injection and NMR etc., the paper studies the type and structure of the micropores in the 4th member of Dengying formation in the study area, and analyzes the relationship between movable fluid saturation and micropore structure. The results show that the accumulation spaces in the study area are dominated by intergranular dissolved pore, residual intergranular pore, intercrystalline pore and dissolved cave with the average total surface porosity of 2.5%; various pore combinations have different micropore structures, among which the pore structures of the reservoir dominated by intergranular dissolved pore–residual intergranular pore are the best, and the displacement pressure and median pressure are 4.1 MPa and 18.7 MPa, respectively, which are relatively low. The average pore throat radius is 0.059 μm and the movable fluid saturation is relatively high, which is 41.5%. The permeability and the development degree of intergranular dissolved pore are the key factors influencing movable fluid saturation which shows a positive correlation with radius and connectivity of pore throat