In view of the low permeability reservoir after fracturing development that can cause the asymmetrical vertical fracture, the productivity of this oil well is little information. Thus based on the steady seepage theory, with the aid of conformal transformation method, a prediction model for the finite-conductivity asymmetrical vertical fracture wells was established, and the various factors on the productivity of oil well were analyzed, under the influence of the start-up pressure gradient in the low-permeability oil reservoirs. The result shows that the decrease of productivity decreases is caused by start-up pressure gradient. In the same start-up pressure gradient, the productivity decreases with the increase of the production pressure. When the conductivity capacity of fracture becomes small, there is obviously difference for the productivity of fracture oil well in the crack length and fracture asymmetry factor. And when the conductivity capacity of fracture becomes big, there is little difference for the productivity of fracture oil well in the crack length and fracture asymmetry factor. The longer is the crack length and the less is the fracture asymmetrical factor, the greater is the productivity of the fracture oil well.