NOVELTY - A ethylene cracking raw material preparing method involves hydrogenating light C5 fraction raw materials by subjecting the light C5 fraction to hydrogenation reaction through a hydrogenation catalyst fixed bed in the presence of hydrogen to convert unsaturated hydrocarbons in the light C5 fraction raw materials to saturated hydrocarbons to obtain a hydrogenation reaction product, which is returned as solvents to the hydrogenation catalyst fixed bed together with the raw materials after being mixed with the raw materials. The hydrogenation reaction product is desulfurized.    USE - Method for preparing ethylene cracking raw material.    ADVANTAGE - The method enables preparing ethylene cracking raw material with better utilization of the desulfurizer and the hydrogenation catalyst.    DETAILED DESCRIPTION - An ethylene cracking raw material preparing method involves hydrogenating light C5 fraction raw materials by subjecting the light C5 fraction to hydrogenation reaction through a hydrogenation catalyst fixed bed in presence of hydrogen to convert unsaturated hydrocarbons in the light C5 fraction raw materials to saturated hydrocarbons to obtain a hydrogenation reaction product. The hydrogenation reaction product is returned as solvents to the hydrogenation catalyst fixed bed together with the raw materials after being mixed with the raw materials. The hydrogenation reaction product is desulfurized by a desulfurizer fixed bed before being mixed with the raw materials under volume liquid hourly space velocity of 3.0-16.0 hr-1, pressure of 0.2-0.6 MPaG and feeding temperature of 5-60 degrees C, where the weight ratio of the raw material and the hydrogenation reaction product is 1:6-10, the desulfurizer in the desulfurizer fixed bed is active component loaded modified granular activated carbon, and has grain diameter of 3-6 mm, the active component is cupric oxide and nickel oxide, the concentration of the active components is 1-5 wt.%, the atomic number ratio of copper and nickel is 1:(0.2-0.8).