A novel design algorithm for the steady-state coupled power equations describing stimulated Raman scattering in Multi-wavelength cascaded Raman fiber lasers has been proposed. By taking the advantage of genetic algorithm and shooting method, a few elite individuals with the best fitness on each generation are chosen to implement several shootings to accelerate theirs converging. As an example, the output characteristics of an all-fiber three-wavelength (1427 nm, 1455 nm, and 1480 nm) Raman fiber laser with 500 meters P2O5-doped fiber as gain medium and fiber Bragg gratings as resonators has been analyzed with the algorithm. The results show that the total output power linearly depends on the pump power approximately with a slope efficiency of ～51%; the slop efficiency of longer wavelengths is larger than that of the shorter wavelengths due to the longer wavelengths gain additional power at the expense of the power of the shorter wavelengths.