Low permeability reservoir has a lower permeability, hydraulic fracturing is often used to improve the productivity of the well. The evaluation of the productivity of fracturing well is essential to the development of the low permeability reservoir. On the basis of a new model which describes the low-velocity nonlinear seepage law, the formulas are established for the vertical fractured wells with both infinite and finite conductivity. A comparison and analysis are made on productivity between Darcy’s model and start-up pressure gradient model. The results show that there are some differences on productivity only under very low production pressure difference, and with the pressure difference increasing, and the fracturing well productivity predicted by three models becomes almost same. The productivity of fracture with finite conductivity that is equivalent to the vertical well productivity makes it easy for engineering practice. Results show that the equivalent vertical well radius increases with dimensionless conductivity increasing and decreasing of dimensionless oil drainage radius.