Self-excited-oscillation pulsed abrasive flow polishing method is mainly used to polish the inner surface of cavity parts. To further improve the polishing efficiency through enhancing self-excited oscillation pulse characteristics of the polishing liquid, a polishing method based on abrasive flow of double self-excited oscillation cavity is proposed. By using the double self-excited oscillation cavities connected in series, the self-excited oscillation pulse characteristics of the polishing fluid were further enhanced, and the peak velocity and turbulent kinetic energy of the polishing fluid were also increased. The pulse characteristics of double self-excited oscillation cavity was analyzed by numerical simulation, and a polishing experimental platform was established for abrasive flow of double self-excited oscillation cavities connected in series. Experiments verified the effectiveness of the double self-excited oscillation cavity to improve the pulse characteristics of the polishing liquid. Simulation results show that the double self-excited oscillation cavity has an effect of increasing the peak velocity, from 66.8 m/s to 76.8 m/s. The experimental results of polishing the inner surface of a 6 mm diameter stainless steel tube show that:under the same experimental conditions, after processing for 10 hours, the roughness Ra of the inner surface of the workpiece polished by the double self-excited oscillation cavity was reduced from 452 nm to 42 nm and the inner surface had a significant mirror effect; while the roughness Ra of the inner surface of the stainless steel tube processed by a single self-excited oscillation cavity was reduced to 100 nm, and the inner surface was relatively dark, and it needed to take another 2 hours for reaching 42 nm. At the same time, the experiment also proves that the pulse characteristics of the fluid was attenuated in the flow channel. The effectiveness of abrasive flow polishing of double self-excited oscillation cavity was proven by numerical simulation and experimental analysis, with the effect of further enhancing the peak fluid velocity and turbulent kinetic energy. In order to make full use of the self-excited oscillation pulse characteristics, the workpiece needs to be installed near the downstream outlet of the cavity.