Most tight oil reservoirs are put into production by multistage fractured horizontal well，and the distribution of the natural fractures and hydraulic fractures，and the coupling of the fractures and matrix should be considered in the productivity analysis. A model of the horizontal wellbore，and the distribution of the hydraulic fractures and natural fractures is proposed by the COMSOL and MATLAB program based on the real data of the fracture strike and density in S Oilfield. The pressure distribution，daily oil production and cumulative oil production under the different lengths and spacing of hydraulic fractures are simulated by the matrix-fracture-wellbore coupling flow model. The results show that the pressure drops can be firstly observed in the main fractures and secondary fractures with higher conductivity，and then pressure drops spread to the natural fractures and matrix slowly. Pressure drop is hard to spread to the unstimulated and disconnected reservoir regions. The low-pressure area accounted for 34.1% of the whole reservoir area when the production time is 1 000 days. Increasing fracture length and decreasing fracture spacing are helpful to the improvement of both daily and cumulative oil production. Decreasing the fracture spacing is a more effective way to increase the daily oil production so that the cumulative oil production is improved significantly.