A graphical method is proposed to optimize the two-stage pyrolysis gasoline (pygas) hydrogenation reactor based on the hydrogen network integration. The relation between the hydrogen utility adjustment (HUA) and the parameters of pyrolysis gasoline (pygas) hydrogenation reactor in different situations is deduced based on the hydrogenation reaction kinetics and integration of hydrogen network, and the variation of HUA with temperature is analyzed with the proposed quantitative diagrams. Based on this method, the temperature of first-stage and second-stage reactors can be optimized separately or simultaneously, and the product quality can be taken into consideration to make the results more accurate. The case study shows that this method can identify the optimal reaction temperature in each stage reactor accurately under different conditions and can give significant guidance for pygas hydrogenation unit design and improvement.