Abstract: Based on the basic principle of fluid mechanics, three-dimensional finite volume models of a slab continuous casting mold and a submerged entry nozzle (SEN) were established by Fluent software. When the nozzle was off-center and clogging, the flow characteristics of fluid and temperature field distribution in the mold were investigated. The results showed that while the nozzle was off-center, circulation flows in both sides of the mold were asymmetric and there were vortexes in the free surface. The temperature in the side which was near to the nozzle was higher than that in the other side. When one port of the nozzle was clogging, molten steel from the other port enhanced and the velocity of surface flow from the other port would increase, with vortexes in the free surface. Fresh molten steel from the clogging port reduced and the temperature near to the clogging port was relatively low.