The numerical simulation of SiC sublimation growth was carried out. On the results of flux control growth with innerguide tube, the tube controls the thermal field inside a growth cavity, and makes it possible to grow single crystal without obstacle polycrystal. It was also cleared that the grown crystal shape strongly depends on the temperature distribution inside a growth cavity. On the results of in-process etching, it was pointed out that defects occurrence can be suppressed by taking care of temperature distribution on the initial growing surface. These results show that by controlling the thermal field inside a growth cavity, it is possible to control the macro and micro crystal quality such as grown crystal shape and defects, respectively.