In view of the unconventional permeability and porosity of the low permeability gas reservoir, fractured horizontal well becomes the essential to achieve satisfactory production. Based on the actual flow of fractured horizontal well, this paper establishes an equivalent well diameter model of the single fracture horizontal well. Then, according to the superposition rule, the paper set up a complete model of multiple fracture horizontal well, and couple the model with the horizontal flow dynamic. After that, this paper gives the iterative algorithm about the model, and programs the model in the C# environment. Finally, this paper confirms the reliability of this model through a practical example, and gives some applications of this model to optimize hydraulic fracturing.