The jet plume effects on sonic boom for hypersonic slender bodies are studied systematically for the first time by simulating nose cone and nose double-cone geometries. The jet plume effects on hypersonic sonic boom are found to be different from the effects on low-supersonic sonic boom because the significantly smaller leading shock angle makes the shock directly interact with the underexpanded jet plume. When sufficiently underexpanded, the jet-induced shocks and shear layers significantly amp