The invention provides a method of preparing a nitrile butadiene rubber reinforcing agent through an olefin metathesis catalyst and preparing high-strength nitrile butadiene rubber by graft-polymerizing nitrile butadiene rubber latex with the nitrile butadiene rubber reinforcing agent. In the invention, firstly the nitrile butadiene rubber reinforcing agent having excellent reaction activity with the nitrile butadiene rubber latex is synthesized through the steps of mixing a cyano compound containing an alkene or alkyne unsaturated substituent group with an organic silioxane monomer containing the alkene or alkyne unsaturated substituent group, and with a methylbenzene solvent, adding an olefin metathesis catalyst, insulating air and water, and performing a normal-temperature reaction, and separating the solvent through a vacuum desolventizer to prepare the nitrile butadiene rubber reinforcing agent. The nitrile butadiene rubber reinforcing agent and the nitrile butadiene rubber latex are fed into a polymerization kettle according to ratio with addition of an initiator, and performing a reaction with reaction temperature controlled for a certain time, and coagulating, washing and drying a product to obtain the high-strength nitrile butadiene rubber.