The invention relates to a modification method of catalytic
gasoline. Under the effect of a pre-hydrogenation catalyst,
sulfur alcohol etherification and
double bond isomerism reactions are carried out on
gasoline through a pre-hydrogenation reactor, an
effluent of a pre-
hydrogenation reaction is
cut and fractionated into light and weight components, an isomerism reaction is carried out on the light component under the effect of an isomerism catalyst, the heavy component enters a desulfuration-
octane value
recovery reactor, a
hydrogen desulfurization-isomerism catalyst and an
octane value
recovery catalyst are loaded inside the reactor, the heavy component is firstly in contact with the
hydrogen desulfurization-isomerism catalyst, a selective
hydrogen desulfurization-isomerism reaction iscarried out under the effect of the hydrogen desulfurization-isomerism catalyst, and simultaneously,
straight chain olefin is isomerized into single branched chain olefin or single branched chain paraffin; the heavy component after the reaction is then in contact with the
octane value
recovery catalyst to carry out a double branched chain isomerism reaction; and finally the light and heavy fractions are blended to obtain a
gasoline product with low olefin, ultra-low
sulfur content and high octane value. The hydrogen desulfurization-isomerism catalyst and the octane value recovery catalyst arearranged inside the same reaction device, and the technology is simplified.