Abstract: Full-scale water modeling experiments were carried out to investigate the transient fluid flow in a CSP funnel-shaped mould under a bilateral hole submerged entry nozzle (SEN). The results show that molten steel level is unsteady and the level fluctuation has a periodical exacerbation, which is called meniscus dynamic distortion (MDD). The relationship between process parameters and MDD was discussed. Tracer experiments were used to study the flow characteristic of molten steel in the mold. It is concluded that the turbulent kinetic energy assembling and rapid dissipating from bottom to meniscus cause the MDD.