A description is provided for a new patented design of a slab crystallizer and its cooling system with calculation results and identified shortcomings obtained previously. In the work using Autodesk Simulation CFD software, heat transfer is simulated in slab molds of two designs with different wall materials and cooling systems. Melt is supplied to the crystallizer through a submersible deep-bottom nozzle with two outlets. Results of heat transfer modeling using the program are presented in the form of temperature distribution along the length of the mold wide wall. Workpiece crust thickness is considered according to previous calculation results. Maximum values of wall temperatures obtained are comparable with calculations performed previously. Based on results of the color images shown in pictures of the wall surface temperature maximum and minimum values, temperature differences along the length of the walls are established, which are compared for various mold designs, cooling systems, and wall materials. Use of the new slab crystallizer permits an increase in wall working surface temperature up to 300 degrees C and a reduction in temperature drop along the length of the wide wall by a factor of 4-5 compared with the existing copper design of the slab crystallizer. The result obtained points to the possibility of preparing highly-alloyed steel slab billets with a better surface.