Abstract: In order to obtain dual-wavelength output with different intervals, an equipment to generate dual-wavelength laser based on simulated Brillouin effect was put up. The tunable microwave signal was got through beat frequency experiment for the different intervals dual-wavelength output signal. A segment of 10 km single-mode fiber (SMF) was used as the Brillouin gain medium and a 5 kHz distributed feedback (DFB) semiconductor laser was used as the Brillouin pump (BP). An un-pumped polarization maintaining erbium-doped fiber (PM-EDF) was used as the saturable absorber to suppress unwanted side-modes. Different-interval dual-wavelength output was obtained by changing the length of un-pumped PM-EDF. In the experiment, dual-wavelength outputs with 0.170 nm and 0.085 nm spacing were achieved, corresponding to 20 GHZ and 10 GHZ microwave signals.