In this experiment, a dual-color passive synchronous all-polarization-maintaining fiber laser is demonstrated, which can generate wide spectrum for coherent anti-Stokes Raman scattering detection. The laser is composed of Yb-doped and Er-doped fiber lasers. Stable passive synchronization state can be achieved within 150μm cavity length mismatch distance by injecting synchronization. The spectrum of Er-doped laser can be broadened to 1000~1700nm by a highly nonlinear fiber, Then the Er-doped laser is temporally and spatially combined with Yb-doped laser to generate a sum-frequency signal through nonlinear crystal. The passive synchronous dual-color fiber laser can be used as a stable and ultra-fast light source for the detection of coherent anti-Stokes Raman scattering and is expected to realize the simultaneous detection of multiple Raman peaks in the wide spectrum.