Abstract: According to flow characteristics of different flow areasof fractured horizontal wells in low permeability oil reservoirs, the vadoseregion of fractured horizontal wells can be divided into threedistricts, the non-Darcy flow district with a high speed controlled bycracks, the ellipseflow district and the matrix non-Darcy flow district. Two-phase porous flowmathematical models of matrix non-Darcy flow with start-up pressuregradient are built. The results indicate that the production goes with theincrease of fracture conductivity; the incremental scope of production decreaseswith the increase of production time; initial production of fracturedhorizontal decreases progressively with the increase of fracturelength, the incremental scope of production decreases with the increase offracture length; the production of fractured horizontal wells is the maximum in thesituation with a long median crack and a short two-way crack.