Abstract: The S-Zorb process can reduce the sulfur content of gasoline to less than 10μg/g. However, the hydrogenation reactions of olefins and aromatics occur inevitably during S-Zorb adsorption desulfurization, leading to some octane number loss. In order to optimize the S-Zorb operation, the comparative analysis of the compositions of feed and product of S-Zorb unit of Shanghai Gaoqiao branch was conducted to see the influence of hydrogenation reactions on change of compositions from the point of view of thermodynamics and kinetics. The equilibrium constants and Gibbs free energies at different temperatures were calculated under the normal pressure. And the reaction rate constants were figured out by the 4th order Runge-kutta method.