Phosphite is an efficient processing aid, which can effectively prevent oxidative degradation of polymer materials during processing, and prevent discoloration and mechanical strength decline caused by oxidative degradation during processing. The product has the characteristics of high efficiency, low volatility and low color influence, and is especially suitable for polyolefins, such as polyethylene, polypropylene, polybutene and other polymers, such as polyethylene, poly amide, polyurethane, polyester, polyvinyl chloride and polystyrene, various elastomers, coatings and other polymer materials.