Based on gas flow theory in porous media, this paper has considered the formation damage and non-Darcy flow effect and obtained binomial productivity equation in the form of pressure square. Therefore, we can predict inflow performance relationship (IPR) curve, the absolute open flow potential, and production performance of horizontal gas wells by binomial productivity equation. At the same time we study the influences of the gas reservoir bed thickness, anisotropism of the gas reservoir on the IPR curve, and the absolute open flow potential for the example horizontal gas well.