A technology for growing silicon carbide single crystals by PVT (Physical Vapor Transport) and a technology for in-situ annealing the crystals after growth is finished is provided. The technology can achieve real-time dynamic control of the temperature distribution of growth chamber by regulating the position of the insulation layer on the upper part of the graphite crucible, thus controlling the temperature distribution of growth chamber in real-time during the growth process according to the needs of the technology, which helps to significantly improve the crystal quality and production yield. After growth is finished, the inert gas pressure in growth chamber is raised and the temperature gradient of the growth chamber is reduced so that in-situ annealing the silicon carbide crystals can be carried out under a small one, which helps to reduce the stress between the crystal and the crucible lid as well as that in sublimation grown crystals to reduce the breakage ratio and improve the yield ratio during the subsequent fabrication process.