A multi-wavelength single-frequency optical fiber laser source for a laser radar system includes a resonant cavity composed of a high-reflectivity chirped optical fiber grating, a high gain optical fiber and a low-reflectivity chirped optical fiber grating, a single-mode semiconductor pump laser served as a pump light source, an optical wavelength division multiplexer, an optical coupler, an optical isolator, an optical circulator, an optical filter module, and a semiconductor optical amplifier. The pump light source performs optical fiber core pumping with respect to the high gain optical fiber. A portion of the wide-spectrum laser is filtered by the optical filter module to obtain a wavelength corresponding to a specific central frequency. Multi-wavelength laser lasing with a narrow linewidth and single longitudinal mode is implemented by combining a short linear resonant cavity structure and the optical filter module.