A hydrothermal reactor is a closed vessel that can decompose poorly soluble substances. It can be used for dissolution sample pretreatment in atomic absorption spectroscopy and plasma emission analysis; It can also be used for small doses of synthetic reactions; It can also use the strong acid or alkali in the tank and the high temperature and high pressure closed environment to achieve the purpose of rapid digestion of insoluble substances. It is a powerful assistant for digestion of samples when determining trace and trace elements. It can be used in the determination of heavy metals such as lead, copper, cadmium, zinc, calcium, manganese, iron, mercury, etc., and can also be used as a reaction vessel with high temperature resistance, high pressure and anti-corrosion and high purity, as well as organic synthesis, hydrothermal synthesis, crystal growth or sample digestion and extraction. Digestion of heavy metals, pesticide residues, food, sludge, rare earths, aquatic products, organic matter, etc. before sample treatment. Therefore, it is widely used in the research and production of petrochemical, biomedical, material science, geochemistry, environmental science, food science, commodity inspection and other departments.