The main influence of the inclusion removal rate by gas curtain were analyzed. The technical arrangement of gas curtain and the flow control device in the tundish were optimized according to the results of water model experiment.The gas curtain of dispersion magnesium was developed， and intelligent control technology and technology of surface covered with argon blowing for gas curtain was developed， etc. Some key technical problems that restrict the low removal rate of inclusions in gas curtain are overcome. The inclusion ratio of argon blown by gas curtain is less than 50% that of non blowing argon .