Abstract: During waterflooding development in tight oil reservoirs, high-permeability channels and induced fractures tend to form along high-permeability pathways due to reservoir heterogeneity. However, existing well test interpretation methods cannot adequately analyze interwell interference well test data under waterflood-induced fracture conditions. This study establishes a numerical well test model for waterflood-induced fractures coupled with a stress field model at the fracture tip, accounting for interwell interference. The model employs unstructured grids and the discrete fracture model (DFM) to characterize dynamic fractures, obtaining bottom-hole pressure solutions for numerical well testing. Typical well test type curves are generated, and sensitivity analyses are conducted. The results indicate that lower fracture conductivity leads to a less pronounced "concave" effect during fracture channeling flow. Under interwell interference conditions, adjacent injectors cause a significant late-time pressure drop in the type curves. Smaller well spacing and higher injection rates accelerate and amplify the pressure and pressure derivative decline, making interference characteristics more evident. The proposed numerical well test method is applied to field pressure data, successfully determining the petrophysical parameters of high-permeability channels and through-well fractures, thereby validating its applicability and reliability.