Shale gas reservoirs are commonly developed using horizontal wells with multistage hydraulic fracturing. During production, the flowback efficiency of fracturing fluids is generally low, resulting in substantial fluid retention within the fracture networks created by fracturing. The retained fluids interact with the shale matrix, inducing alterations in its physical properties, which subsequently impair fracture conductivity and permeability and ultimately affect gas well productivity. However, the invasion depth, invasion rate, and controlling factors of fracturing f luids into the shale matrix remain poorly understood. In this study, deep shale samples from the Da’an block in the Sichuan Basin were investigated using a Nuclear Magnetic Resonance (NMR) monitoring system under high-temperature and high-pressure conditions. A series of experiments were conducted to systematically examine the dynamic invasion behavior of frac turing fluids under different permeability, temperature, and confining pressure conditions. The results indicate that the invasion depth of fracturing fluids is primarily limited to approximately 30 mm. Higher permeability significantly accelerates the invasion rate and extends the invasion distance. The invasion process exhibits a distinct three-stage behavior, in which fracturing fluids preferentially invade smaller pores at the early stage under capillary force dominance, followed by gradual invasion into larger pores. Temperature and confining pressure exert significant control over both the invasion rate and invasion volume: higher temperatures and lower confining pressures promote faster invasion and greater fluid uptake. In addition, the presence of gas within pores suppresses fracturing fluid invasion, resulting in a reduced invasion volume, while exerting a negligible influence on the invasion depth. These findings provide experimental insights into the invasion mechanisms of fracturing fluids in deep shale and offer guidance for optimizing f lowback strategies in shale gas reservoirs.