A tunable Optoelectronic Oscillator (OEO) based on stimulated Brillouin Scattering (SBS) and Coupled Dual-Loop (CDL) is proposed. The OEO combines SBS and CDL. The narrow bandwidth gain spectrum of SBS is employed to select the oscillation frequency and realize frequency tunability. By the join of CDL, the side mode of the microwave signal is effectively suppressed, the phase noise of the microwave signal is decreased, the frequency and power stability of the microwave signal are improved. Experimental results show that microwave signals from 2 GHz to 18 GHz with the Side Mode Supression Ratio (SMSR) as high as 60 dB and the phase noise as low as -95 dBc/Hz at 10 kHz frequency offset are achieved. The frequency drift is less than 0.3 ppm and the power drift is lower than 0.2 dB at 10 GHz within 30 min in lab condition.