A 3-D comprehensively coupled model has been developed for iron-carbon binary system to describe the turbulent fluid flow, solidification and solute transport in the parallel type mold of thin slab. In order to calculate the boundary conditions at the exit of the submerge entry nozzle (SEN), a 2-D model was built according to the practice conditions of bifurcated SEN. The calculated results show that the depth of the injection flow from the SEN into the parallel type mold is much smaller than that in the conventional slab caster due to the small thickness of the thin slab. The jet flow from the SEN impinges on the wide wall strongly especially near the corner of the mold but cannot reach the narrow wall. A nearly-uniform flow field is obtained at the exit of the mold. Under the common action of the fluid flow, solidification and solute distribution, the thinnest thickness of the solid shell on the wide wall appears near the corner and the concentration of carbon changes steeply at the mold exit. This maybe the reason for the very often happened accident of out-of-corner breakout.