In order to quantitatively characterize the effect of osmotic pressure on the imbibition displacement of the tight sandstone reservoir，a semi-analytical mathematic model for the imbibition of tight sandstone reservoir considering the osmotic pressure was established based on the capillary force function and the osmotic pressure equation. Based on the established model，the parameter sensitivity of imbibition salinity，maximum relative permeability of water phase and oil phase，relative permeability coefficient of water phase and oil phase and oil-water viscosity ratio were analyzed and compared with the core experiment results so as to correct the model parameters. The research indicates that the effect of imbibition displacement is more obvious when the salinity difference of reservoir fluid and imbibition fluid is larger，and the osmotic pressure mainly affects the middle position of the imbibition displacement. The order of parameters influencing the imbibition is as follows：the relative permeability coefficient of water phase>the maximum relative permeability of water phase>the ratio of oil-water viscosity>the relative permeability coefficient of oil phase>the maximum relative permeability of oil phase.The oil-water viscosity ratio has the most significant influence on the salinity distribution. The relative permeability coefficient of water phase and maximum relative permeability of water phase mainly affect the salinity distribution of the propulsion front. The relative permeability coefficient of oil phase and the maximum relative permeability of oil phase have almost no effect on the salinity distribution. The correction coefficient of the imbibition displacement model is about 0.7. The correction coefficient of the stable imbibition time has a good linear correlation with the maximum relative permeability of water phase.