Vacuum drying, also known as analytical drying, is a drying method that places the material under negative pressure conditions and appropriately heats it to the boiling point under negative pressure, or cools it down to solidify it and then dries it through the melting point. The melting point and boiling point of the water in the material under negative pressure decrease with the increase of vacuum degree. At the same time, the vacuum pump is used to dehumidify the gap to reduce the water vapor content, so that the water and other solutions in the material can obtain enough kinetic energy to leave the surface of the material. Vacuum drying isolates the air under negative pressure, so that some materials that are prone to oxidation and other chemical changes during the drying process can better maintain their original characteristics. The material can also be better protected by injecting inert gas and then evacuating the vacuum. Common vacuum drying equipment includes: vacuum drying oven, continuous vacuum drying equipment, etc.