Steel strip feeding into the mold during continuous casting is known as an innovative technology. The newly applied technology is designed to further improve the slab quality. To analyze the complex phase change processes, molten sodium thiosulphate (Na2S2O3·5H2O) was used in the experimental investigation as a transparent analog for metallic alloys. Then, a numerical model incorporating fluid flow, heat transfer and phase change during strip feeding into the mold process was developed. The generalized enthalpy-based method was applied to describe the phase change behavior, and the porous media theory was used to model the blockage of fluid flow by the dendrites in the mushy zone between the strip and melt as well as the solidified shell and melt. The validated model was then used for the simulation of the real strip feeding into the mold process in an industrial scale. The whole shape of the strip under the effect of jet flow from the submerged entry nozzle (SEN) was presented. Results show that the strip will reach a pseudo-steady state after experiencing steel sheath formation, steel sheath melting and strip melting processes. When using the feeding method that is the strip narrow side toward the SEN in the present condition, the strip immersion length can reach 4.5 m below the meniscus and the slab centerline temperature can be decreased by 21 K to a maximum. When the strip feeding speed increased from 0.3 to 0.5 m/s, the minimum temperature of the centerline could be lowered by 4 K or so.