Abstract: The relative permeability regularity study of shale gas reservoirs has a significance in the recovery prediction of this reservoir.Although the liner function proposed by Romm is still widely used in the calculation of relative permeability to predict the gas recovery,lots of researches have manifested this function will lead to a serious deviation from the real situation. In this paper, a new model for calculating oil/water two phase relative permeability curves of shale gas reservoir is proposed, which is related to the effect of fluid saturation and viscosity. Compared with Romm model, the new model can be better used for percolation estimation of shale gas reservoirs