Abstract: The interactions among CO2, water and rock will result in wettability changes of reservoir rocks after CO2 is injected into formations, which will impact reservoir permeability. Contact angle and interfacial tension (IFT) measurements, and core displacement experiment are used to study the influence of CO2-water-rock interactions on the sandstone reservoir wettability under high pressure, and to investigate the relationship between rock wettability and permeability. The results show that the static water contact angle on the surface of quartz increases gradually with the increase of CO2 pressure and reaches the maximum when the pressure of CO2 is 7.2 MPa, then gradually reduces with the increase of CO2 pressure; water-CO2 interfacial tension and water adhesion work on the quartz surface gradually decrease with the increase of CO2 pressure and reach the minimum when the pressure of CO2 is 7.2 MPa, then increase with the increase of CO2 pressure. With the decrease of pH value of aqueous solution, the contact angle of water on quartz surface first decreases then increases, and reaches the maximum when the pH value reduces to 2.5. When the pH value continuously decreases, the contact angle reduces. With the decrease of the pH value of aqueous solution, the contact angle of water on sandstone surface first decreases and then increases, and the water permeability in the sandstone first decreases and then gradually increases.