Physical modeling of argon shroud was carried out using a 2D 1:1 scaled model in order to gain the protection effect in steel casting. The speed field of protective gas around the steel steam was measured by PIV technique. The oxygen distribution was measured by an oxygen sensor. The main findings are following: (1)The distance between the ladle and the collar should be minimized to reduce the oxygen entrainment.(2)For single inlet, the oxygen contents were lower in the case of horizontal gas inlet than vertical gas inlet.(3)A dual gas inlet configuration would be more effective than a single inlet in ordinary operation conditions.