Based on non-Darcy gas seepage characteristics in porous media, a new productivity equation was presented for tight reservoirs in pseudo-steady state considering the effect of power function stress sensitivity. And the open flow capacity calculation formula of gas wells was derived. The computation result of an example showed that: the stress sensitivity phenomenon reduced the productivity and open flow capacity of gas wells in pseudo-steady flow period. The productivity curve of producer bended towards the pressure axis and the productivity was lower than that calculated from the equation without stress sensitive coefficient under the same producing pressure drop. The larger the power function stress sensitive coefficient was, the earlier and severer the productivity curve bended, and the lower the productivity was and the larger the yield reduction rate was. With the decline of reservoir pressure, the effect of stress sensitivity would be reduced for producing well. It would be appropriate to enlarge producing pressure drop when the average formation pressure was lower.