In order to solve the problem that the pressure drop curve or the pressure recovery curve made by measured data was not fitting well with the classic model curve in low permeability reservoir, on the basis of previous studies and nonlinear flow of power law model, the method of differential discrete was used to build a quick and precise method for calculating the pressure, and the calculation method of dynamic permeability and conductivity was also investigated in detail. The factor of pressure curve model was analyzed by using control variable method. The result showed that the bigger the powerlaw index was, the greater the bending upwards magnitude of the pressure curve model was; with the coefficient of the wellbore storage and skin factor becoming larger, the reservoir fluid in low permeability reservoir cost more time to flow into steady flow; for closed boundary reservoir, the pressure model curve upturns and the reservoir resolution points were very clear. The pressure curve and the pressure derivative curve intersected. For the constant pressure boundary reservoir, it was on the contrary with the closed boundary reservoir, but after the fluid flows into the quasi steady state of radial flow, model curves were a cluster of parallel inclined lines.