Silicon carbide (SiC) epitaxial process is a key step in the fabrication of power devices, and the temperature field inside the reactor chamber plays an essential role in this process. In this paper, the temperature field in the horizontal chemical-vapor-deposition reactor chamber used for growing homo-epitaxial 4H-SiC material is studied using the finite-element method. A three-dimensional time-dependency model is built for the accuracy of simulation, and the effects of 11 relative coil locations (−50, −28, −18, −10, −4,0,4,10,18,28, and 50 mm) on heating efficiency and temperature uniformity of the substrate are analyzed. Results indicate that the suitable relative location between the center of coil and that of the substrate to achieve optimum temperature uniformity is −4 mm, and 18 mm to obtain the highest heating efficiency. To increase the heating efficiency and temperature uniformity of the substrate, the structure of the reactor was analyzed and optimized. It is observed that both heating efficiency and temperature uniformity can be effectively improved by adding a graphite pillar inside the down susceptor.