Inhibitor 701 is a new type of free radical polymeric inhibitor with high efficiency and wide application. It has good blocking effect under the condition of oxygen without oxygen. The product is used to prevent polyolefin monomers from self-polymerization during production, separation, refining, storage or transportation, and to control and regulate the degree of polymerization of olefin and its derivatives in organic synthesis. The product has good polymerization resistance to acrylate, methacrylate, acrylic acid, acrylonitrile, styrene and butadiene.