Aiming at the problem of strong mutual interference during the expansion process of volume fracturing fractures in tight oil blocks in the Songnan Basin, based on the principle of limited flow fracturing, a numerical model of volume fracturing that fully considers the mutual interference of fractures is established. The model describes the fluid–structure coupling through the solid equation system of crack propagation and rock mass deformation and the fluid equation system of fluid flow and fluid loss in the fracture. The finite element method is used to discretely solve the equation, and the accuracy parameter optimization of the model is verified based on both theoretical and engineering methods. The model was applied to simulate and analyze the influencing factors of the initiation and propagation morphology of multiple clusters of fractures in volume fracturing. The research results showed that pumping rates and the perforation clusters spacing were the main influencing factors on the propagation morphology of fractures, while the number of perforations had a relatively small impact on the size of fractures after fracturing. The study established a full three-dimensional volume fracturing finite element model with dynamic pumping rates distribution and mutual interference of fractures, which provides a theoretical basis for the design and optimization of volume fracturing construction plans for tight oil in the Songnan Basin and related characteristics.