The pour point depressant is a chemically synthesized polymer or condensate, which generally contains polar groups (or aromatic nuclei) and alkyl chains similar in structure to paraffin hydrocarbons in its molecules. The pour point depressant cannot prevent the crystallization of paraffin at low temperature, that is, the cloud point of the oil remains unchanged. It changes the shape and size of the wax crystal through adsorption on the surface of the wax crystal or eutectic with the wax, preventing the wax from forming a three-dimensional network structure so that it still maintains the ability of the oil to flow at low temperatures. It should be emphasized that the pour point depressant can only function in the oil containing a small amount of wax, and the oil without wax or too much wax will have no pour point depressing effect. The most commonly used pour point depressant is methyl dimethacrylate