The shale gas reservoir in Changning Block of Sichuan Basin has entered the stage of three-dimensional development. The main production layer of Longmaxi Formation adopts the “W” shaped upper and lower horizontal wells for three-dimensional development, and the well spacing was reduced from the initial 500 m to 300 m. With the reduction of well spacing and the deployment of three-dimensional development well locations, the interference caused by cross well fractures often occurs and even causes cross well pressure channeling, resulting in the decline of adjacent well productivity. In order to explore the interwell interference mechanism of complex fractures in cube development wells. The idea of geological-engineering integration was considered, the comprehensive geological structure and geomechanics model of the Ning209X1 cube development platform, the discrete fracture network model of natural fractures, and the three-dimensional numerical model of complex fracture propagation in hydraulic fracturing were established. The fracture morphology of the four wells in Ning209X1 platform are simulated. And the inter well fracture interference mechanism was analyzed. The results show that the hydraulic fracturing fracture of the platform is difficult to interfere with the adjacent wells in the transverse direction, and the fractures are difficult to propagate through layers in vertical direction. In a few fracturing sections, the clusters of fractures appear uneven initiation and propagation, while in some fracturing sections, asymmetric propagation occurs. Under the current conditions, the distribution of natural fractures is the key factor to determine whether there is interwell interference. The research results can provide theoretical support for the optimization of fracturing operation parameters of fractured shale gas cube development platform.