A rapid and highly sensitive method for determination of traces of molybdenum in steel material by FAAS with laurtrimonium chloride was described. The droplet is smaller, the number of molybdenum in droplets is enriched and the micelle compounds are formatted with the existence of laurtrimonium chloride. As the result, the sensitivity of determination of molybdenum is enhanced for 46%, the linear range obeys in range of 0～40μg mL-1 for molybdenum and the interference caused by coexistent metal ions is eliminated.