An all-opened double-spacing Brillouin-Raman fiber laser was investigated. A C+L band tunable laser was used as Brillouin pump, a laser diode with 1 455 nm center wavelength was used as Raman pump and 7 km dispersion compensation fiber was used as gain medium. Stimulated Brillouin scattering and Raman amplification were generated in the dispersion compensation fiber simultaneously and the odd-order and even-order Stokes light were obtained at the two ends of the dispersion compensation fiber respectively. The proposed configuration can reduce the insertion loss caused by multiple devices. The largest number of output channels is 186, the tuning range is 28.6 nm and the channel spacing is 0.154 nm. The side mode suppression ratio is enhanced from 14 dB to 20 dB by joining a segment of 4 m Erbium-doped fiber.