The invention provides a method of preparing a reinforcing agent of butadiene styrene rubber with an olefin metathesis catalyst and a preparation method of high-strength butadiene styrene rubber with styrene, butadiene and the reinforcing agent of the butadiene styrene rubber in a ternary polymerization manner. Firstly, the reinforcing agent of the butadiene styrene rubber, which is excellent in reaction activity with the styrene and the butadiene, is synthesized, wherein the reinforcing agent is prepared by: (1) mixing an aromatic compound containing an olefin unsaturated substituent group and an organic siloxane monomer containing an olefin unsaturated substituent group; (2) adding the olefin metathesis catalyst with methylbenzene as a solvent and carrying out a normal-temperature reaction with air and water isolated; and (3) removing the methylbenzene with a vacuum solvent-removing apparatus to prepare the reinforcing agent of the butadiene styrene rubber. The high-strength butadiene styrene rubber is prepared by: (1) adding the styrene, the butadiene and the reinforcing agent of the butadiene styrene rubber into a polymerization kettle according to proportion; (2) adding an emulsifier, soft water and an initiator with control of temperature and pressure of a reaction, and performing the reaction for a certain time; and (3) performing cohesion, a washing process and a drying process to prepare a product of the high-strength butadiene styrene rubber.