Abstract: Pre-injection of water to enhance energy in tight oil reservoirs is an effective means of supplementing formation energy and improving the effectiveness of fracturing treatment. Pre-injection of energy enhancing fluid is of great significance for the initiation and propagation of subsequent fracturing fractures in tight oil reservoirs. The study used a large-scale true triaxial fracturing physical simulation system to conduct fracturing physical model experiments under formation pressure conditions based on artificial tight sandstone rock samples. Combined with acoustic emission monitoring during the fracturing process and surface crack morphology after fracturing, the mechanism of enhanced fracturing rock fracture and expansion was studied. The research results indicate that injecting water before pressure can increase the pore pressure of rock samples near the perforation location, resulting in a 7.1% increase in fracture pressure. The acoustic emission events of conventional fracturing methods are concentrated before and after the rock sample fractures, while there is an acoustic emission response during the energy enhancement stage before the fracturing pressure. The acoustic emission events before and after the rock sample fractures due to the formation of micro cracks are relatively scattered. Conventional fracturing acoustic emission events are mainly characterized by tensile fractures, with relatively simple cracks. Energy enhanced fracturing fractures have complex bending, with a 11% increase in the proportion of shear events compared to conventional fracturing. Shear events are mainly distributed near the turning and branching of fractures. The microcracks generated by energy enhancement before compression open under high displacement, forming a complex fracture network through hydraulic fracturing. The hydraulic fracture complexity coefficient of the rock sample increases by 105% before and after energy enhancement at high displacement. The conclusion indicates that pre-fracturing water injection for energy enhancement can significantly increase the complexity of hydraulic fractures in tight sandstone reservoirs. These findings provide important theoretical support and practical guidance for the optimization design and field application of enhanced energy fracturing technology.