The invention discloses a free-radical initiation method in which an initiator is utilized to perform reaction, and azodiisobutyronitrile hydrazine and an oxidizer serve as free-radical initiators to initiate free-radical reaction under the condition of heating. According to the method disclosed by the invention, the working performance is good, azoisobutyronitrile hydrazine is transferred to azoisobutyronitrile in the process of serving as a free radical, so that a dehydrogenation refinement link is effectively avoided, and the purposes of energy conservation and emission reduction are smoothly reached.