Abstract: Based on the Similarity criteria, series water modeling experiments have been carry out to investigate the fluid flow in the mould of thin slab continuous caster by 1:1 ratio water-modeling simulation systems. SG800 hydraulic test data sampling system is applied to investigate the wave amplitude and impe-tus. In order to satisfy the demand of thin slab caster at high speed, a new structure SEN (Submerged Entry Nozzle)-Dissipation SEN have been invented. The effects of dissipation nozzle's structure, outlets' ratio of area, outlet angle and casting speed on fluid flow in the mould have been investigated. The experimental re-sults proved that the dissipation SEN could satify the need of fluid flow condition in the mould at high speed.