Abstract: To explore the rock breaking law and mechanism of the reservoir stimulation technology by electrothermal chemical energy-gathered shock wave, a group of work have been done. Firstly, based on a clear understanding of the evolution of technological devices, the mechanism of propagation and damage of energy-gathered shock waves in reservoirs was analyzed. Then, by using the JH−2 numerical model of brittle material with dynamic failure and conducting physical simulation tests to verify the simulation method, the repeated impact rock breaking test of the energy-gathered shock wave was carried out, and the influence law and mechanism of different energy-gathered shock wave waveforms on the rock breaking effect were analyzed. Finally, the waveforms of different combinations of shock waves were simulated and optimized. The results indicate that the process of rock breaking by energy-gathered shock waves includes the near wellbore fragmentation buffering stage, the competitive initiation and expansion stage of multiple fractures, and the extension and expansion stage of dominant fractures. The combination of shock wave parameters with a peak pressure of 90 MPa and a pulse width of 15 μs has a good fracturing effect. The combinations of low peak pressure with small pulse width and high peak pressure with large pulse width have a better effect on repeated impact rock breaking, which produces a large number of fractures with long lengths and smaller fracture zones. The research results have clarified the rock breaking mechanism of the reservoir stimulation technology by electrothermal chemical energy-gathered shock waves to some extent, providing theoretical support for field applications.