The invention relates to a method for recycling waste heat of the second-stage reactor outlet materials of a pyrolysis gasoline hydrogenation unit and mainly solves the problem of high energy consumption in the prior art. The method for recycling waste heat of the second-stage reactor outlet materials of the pyrolysis gasoline hydrogenation unit comprises the following steps: putting the second-stage reactor outlet pyrolysis gasoline material of the pyrolysis gasoline hydrogenation unit (7) into a carbon 5 decarbonizing tower (1), discharging the separated carbon 5 light components (1) through a tower top, discharging one part of the heavy components (11) from a tower kettle of carbon 5 decarbonizing tower (1) to a downstream carbon 9 decarbonizing tower, after separating the carbon 9 heavy components, through the one stage hydrogenation and the second stage hydrogenation, after the second-stage hydrogenated outlet materials exchanging heat with the second-stage hydrogenated inlet materials, one part of the heavy components providing a heat source for a reboiler (3) in the centre of the carbon 5 decarbonizing tower and one part separating a second-stage after-condenser (6). The technical solution of the method well solves the problems and can be used for recycling waste heat of the second-stage reactor outlet materials of the pyrolysis gasoline hydrogenation unit.