Methylene chloride has the advantages of strong solubility and low toxicity. It is widely used in the manufacture of safe film and polycarbonate, and the rest is used as coating solvent, metal degreaser, gas smoke spray agent, polyurethane foaming agent, release agent and paint remover. In the pharmaceutical industry as a reaction medium, used for the preparation of ampicillin, hydroxypicillin and pioneer; It is also used in the production of petroleum dewaxing solvent, aerosol propellant, organic synthesis extraction agent, metal cleaning agent, etc.