Abstract: The experiments using synthetic desulphurizer with Aluminum slag ash to increase the efficiency of desulphurization and shorten the LF process time were described.The efficiency of mis desulphurizer and factors influencing its effects were emphatically analysed. The gists of the experiments process were as follows: the optimum control of top slag composition, forming the top slag in ladle eariy, the good deoxidation,increasing the Ar gas shtring strength. The experimental results showed that given the desulphurizers addition among 15~20 kg/t, the average LF process time is shorted 10 min, the average desulpherizing rate is raised 16%.