The unsupported Mo-Co-K sulfide catalysts promoted by La were prepared through ultrasonic technology in non-aqueous medium and its performances for the synthesis of mixed alcohols from syngas were also investigated. The results showed that the catalysts promoted by La exhibited higher CO conversion and selectivity to ethanol than the unsupported Mo-Co-K sulfide catalyst without addition of La did under identical reaction conditions. The catalysts were characterized by N-2 adsorption/desorption, X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Raman, and X-ray photoelectron spectroscopy (XPS).