Based on the power law rheology model of alkali-surfactant-polymer (ASP) fluid, the seepage flow model of ASP flooding for horizontal wells and the variable mass flow model in horizontal wellbore are established. Then the horizontal wells performance prediction model is set up by coupling the seepage flow model and the variable mass flow model. The influence of power law index and consistency factor on horizontal well production has been studied. The results indicate that the IPR curve of ASP flooding is concave upward. The production decreases with increasing of the value of the power law index and consistency factor. In different flooding periods, the IPR curves is different. The corresponding IPR curve should be used to predict the production in different flooding periods. The prediction results can basically meet the actual requirements, which provides a basis for the parameter control of three element composite flooding in horizontal wells. 