[application 1] it is used as solvent and organic synthesis [application 2] it is a non combustible low boiling solvent. It is used for cellulose acetate film-forming, aerosol, antibiotic and vitamin production. It is also used as extractant and metal cleaning agent [application 3] dichloromethane is the raw material for the production of fungicides myclobutanil and miconazole, and it is also a good solvent. Application 4: extraction solvent. For example, it is used to extract caffeine from coffee beans. It can also be used as extraction solvent for hops, spices and oleoresin. Pigment diluent. [application 5] in addition to organic synthesis, the product is also widely used as cellulose acetate film-forming agent, cellulose triacetate drawing agent, petroleum dewaxing agent, aerosol and solvent in the production of antibiotics, vitamins and steroids, as well as cleaning and degreasing agent for metal surface coatings. In addition, it is also used for grain fumigation and refrigeration of low-pressure refrigerator and air-conditioning device. It is used as auxiliary foaming agent in the production of polyether urethane foam and as a foaming agent for extruding polysulfone foam plastics.