Horizontal well + multi-stage fracturing is the premise of commercial development of shale reservoir. The shale reservoir after hydraulic fracturing has a complex fracture network dominated by microfractures and several large hydraulic fractures. Stress sensitivity, starting pressure gradient and nanoconfinement effect widely exist in these complex fracture networks and shale matrix. For this reason, a compositional model that can consider a variety of shale reservoir mechanisms is established. On this basis, each mechanism is analyzed and discussed separately, and sensitivity analysis is carried out. Under the premise of comprehensive consideration of all mechanisms, nine groups of control cases were designed by orthogonal design to simulate the production conditions of real shale reservoir, and the mechanism was studied from three aspects of production rate, production gas oil ratio and pressure filed.