This study adopts a tailpipe noise reduction approach by designing a shock wave-based noise suppression device and conducting numerical analyses of the acoustic fields in the tail jet with the installed device. The multi-cavity configuration induces multiple expansion-contraction processes in the combusting gas, generating oblique shock waves to reduce the total jet pressure and available energy, thereby effectively mitigating noise. Experimental results reveal that the dominant impact of jet noise occurs in the low-frequency range. While the overall trend of sound pressure level remains consistent before and after installing the suppression device, the maximum sound pressure level exhibits a significant reduction. In conclusion, the proposed noise suppression device provides both theoretical insights and practical solutions for weapon noise control.