The invention relates to a preparation method of hydrogenated C9 petroleum resin, which is characterized by comprising the following steps of: (1) preparation of supported noble metal hydrogenated catalyst: preparing by using a coating method, selecting noble metal palladium and platinum and transition metal cobalt or nickel as metal active components, preparing a spherical alumina supporter, then coating the active components of palladium and platinum and transition metal on the alumina supporter, and activating to obtain a hydrogenated catalyst; (2) selective hydrogenation: desulfurizing and denitrifying; (3) high pressure hydrogenation reaction: controlling the weight ratio of resin to solvent to ensure that the concentration of resin is 20-40% by weight, taking chain-like or annular saturated hydrocarbon or aromatic hydrocarbon or hydrocarbon mixture as a solvent, and taking a supported noble metal hydrogenated catalyst as a catalyst, wherein the temperature of the high pressure hydrogenation reaction is 250-350 DEG C, the pressure is 8.0-20.0 MPa and the liquid volume space velocity is 0.5-2h<-1>. The properties of the final product hydrogenated C9 petroleum resin are as follows: Gardner is not more than 1, and the softening point is not smaller than 100 DEG C.