Focused on the water model of ladle, a numerical simulation was carried out to calculate the transport process of two groups and three types of tracer(mathematical tracer: passive scalar; physical tracer: pure water tracer and KCl solution tracer) in flow field. The results show that the transport principle of passive scalar and pure water tracer is basically the same. Compared with passive scalar and pure water tracer, denser KCl solution tracer exhibit different transport process as follows: it flows downward to the bottom of water model, followed by main circulation flow with a higher speed, and moves faster along the bottom of the water model towards gas plume and off-side region, afterwards it flows upward to the small circulation flow near the top of off-side wall. However, owing to the existence of "dead zone" at the bottom of off-side of water model, KCl solution tracer stays longer in this zone. As a result, the transport process that the KCl tracer flows upward along the off-side wall is delayed. Finally, from the figures of mass fraction of tracers at the cross plane of water model and the mixing time at monitor points, it is indicated that KCl solution tracer could complete mixing process much faster than the above mentioned other two tracers.