The fracture morphology of vertical well fracturing in the middle and shallow sandstone reservoirs is generally considered to be approximately circular horizontal fractures, and the microseismic monitoring results in the old area of Daqing Changyuan indicate that horizontal fracture extension has a dominant direction. Therefore, numerical simulation of horizontal fracture propagation law is carried out and a numerical model of horizontal fracture propagation is established. The fracture propagation patterns of heterogeneous reservoirs under different geological and engineering parameters are simulated by the mixed finite element (FEM) and discrete element (DEM) methods, and the main controlling factors affecting horizontal fracture propagation are determined. The results show that the conventional fracturing artificial fractures in the heterogeneous reservoir are non-circular, and the horizontal fractures in the zonal distribution of increasing stress on both sides are elliptical, while the horizontal fractures in the zonal distribution of increasing stress are nearly fan-shaped. When the stress gradient is lower than 0.2 MPa/10 m, increasing the displacement and fracturing fluid viscosity can promote the fracture turning and propagation to a certain extent, and reduce the number of long and short axis differences. However, when the stress gradient is higher than 0.5 MPa/10 m, it is necessary to adjust the leading edge direction of horizontal joint expansion combined with the temporary plugging in the joint to effectively realize the fracture expansion in the direction of high stress. This research achievement is of great significance for the design, construction, and development of vertical well fracturing schemes in mid to shallow sandstone reservoirs in the future.