Abstract: In order to hold up the thin water film formed by cooling process on the surface of a steel plate, an air-seal device is build up at the every row of the air-spray device, which leads the thin water film to flow away from the edge of the plate and gets the flat plate. Some parameters such as volume flux, nozzle width, outlet velocity, the height between nozzle and plate, and single nozzle hold-up water velocity were studied. The reasonable values were chosen, the cost was reduced, and the optimized which help to choose reasonable values, reduce the cost, and then get the optimum hold-up water effect was obtained.