The present disclosure provides a device for preparing a crystal and a method for growing a crystal. The device may include a growth chamber configured to execute a crystal growth; and a temperature control system configured to heat the growth chamber to cause that a radial temperature difference in the growth chamber does not exceed a first preset range of an average temperature in the growth chamber during the crystal growth. The method may include placing a seed crystal and a source material in a growth chamber to grow a crystal; and controlling a heating component based on information of a temperature sensing component, to cause that a radial temperature difference in the growth chamber does not exceed a first preset range of an average temperature in the growth chamber during a crystal growth.