Laser wakefield acceleration, owing to its ability to provide extremely high accelerating gradients, is regarded as a promising approach for realizing compact high-energy electron sources. However, because the electron injection process is highly sensitive to both laser and plasma conditions, beam stability and shot-to-shot reproducibility remain key factors limiting its further development. To improve the stability and quality of the generated electron beams, we carried out an experimental study of laser wakefield acceleration based on an all-optical injection scheme using a laser-driven shock injection mechanism. In this scheme, an injector pulse pre-ionizes and heats the gas target, driving the hydrodynamic expansion of the plasma to form a shock structure, thereby enabling controlled electron injection at the density down-ramp. The experimental results show that, compared with the conventional mechanical approach, the shock generated in this scheme exhibits significantly improved stability. The experiment achieved an electron generation probability exceeding 93% and produced high-quality electron beams with an average energy of about 573 MeV, an average energy spread of about 2.1%, an energy rms jitter of about 3.6%, and an average charge of about 21.4 pC. In particular, this scheme can stably generate high-quality electron beams with few-permille-level rms energy spread, with the minimum single-shot value reaching 0.38%. These results indicate that the HOFI-based all-optical injection scheme has strong potential for producing highly stable, high-quality electron beams in laser wakefield acceleration.

laser wakefield acceleration