The invention relates to a C5 hydrogenated petroleum resin raw material, and a preparation method thereof. The method comprises the following steps: removing below C4 light hydrocarbon fractions in an ethylene cracking C5 product; dimerizing a below C4 light hydrocarbon fraction removed material; carrying out weight removal of a dimerized material to obtain an above C6 hydrocarbon fraction and a weight removed material; sending the weight removed material to a first rectifying tower for separation in order to obtain concentrated isoprene at the top of the tower and concentrated m-pentadiene at the bottom of the tower; sending the concentrated isoprene to a second rectifying tower for separation in order to obtain crude isoprene at the top of the tower and obtain a second rectification residue at the bottom of the tower; carrying out extracting separation of the most crude isoprene to obtain an extraction residue C5; and mixing the less crude isoprene, the concentrated m-pentadiene, the second rectification residue, the above C6 fraction and the extraction residue C5 mixture to obtain the C5 hydrogenated petroleum resin raw material. An apparatus realizes the optimization of the raw material based on the prior art, and the operation is stationary and controllable, so the product quality stability and controllability are guaranteed.