Multistage hydraulic fracturing has become a common well completion for horizontal shale gas wells. Some well test data from horizontal shale gas wells have shown pseudo‐steady flow conditions after a period of production. Considering linear flow from reservoir to fracture and linear flow in the fracture, an analytical model is established to calculate the productivity of horizontal shale gas wells under pseudo‐steady flow conditions. The equations in the analytical model are very simple. The production rates calculated by the analytical productivity model are in good agreement with actual gas wells production rates of a well in North American field and 12‐2 well in Fuling shale gas reservoir of China. Sensitivity analysis with the analytical productivity model shows that the different matrix permeability corresponds to the different reasonable fracture conductivity, and the higher the matrix permeability is, the greater the reasonable fracture conductivity. In the process of fracturing for a well, in order to increase production and save fracturing costs, there is no need to generate high‐conductivity fractures, the reasonable fracture conductivity should be determined based on economic evaluations in the real production process. The analytical model provides a practical way to predict production rate for optimization of fracturing design.