Abstract: The research on flow mechanism and productivity evaluation of shale gas is still in its infancy. Based on the complex pore structure of shale gas reservoir, slip flow and adsorption-desorption of shale gas, Darcy model is modified. Compared with the Darcy model in production steady case, the bottom hole pressure based on non-Darcy flow model is higher than that from the Darcy flow; the pressure from the Darcy flow model decays more exaggerated and than predicted well life was shorter. The modified flowing model can describe and characterize shale gas flowing process more accurately. The results can provide basic parameters for the operation and management of the shale gas reservoir.