Microwave plasma chemical vapor deposition (MPCVD) refers to the introduction of high-purity hydrogen (H2) and methane gas (CH4) into a vacuum chamber to generate a plasma fireball under the action of microwaves,methane gas opens chemical bonds under the action of plasma and becomes free carbon atoms (C) and hydrogen atoms (H),carbon atoms are gradually deposited on the diamond seeds at the bottom of the cavity under the action of powerful plasma, so that the seeds gradually grow thicker and eventually form CVD diamond with the same structure and composition as natural diamond.