Since the conventional crystal growth equipment does not have a feeding function, and the raw materials cannot be replenished during the crystal growth process, the final crystal size is usually subjected to the size of the crucible and the equipment, while the cost of larger size crucible and equipment is high, which restricts the research and development of large size crystal.In this paper, an automatic feeding system is designed, which can supply the same mass of raw materials to the crucible according to the quality of the grown crystal, and ensure that the solid liquid interface in the crucible remains unchanged, so as to achieve the goal of growing largesize crystal in a small crucible, improve the utilization rate of equipment, save energy, reduce production costs, and promote the development of largesize crystal.