The invention discloses a preparing method of a monox-supported nickel base hydrogenation catalyst for oil. According to the preparing method, nickel is used as a main active component, magnesium or iron and rare earth element are used as auxiliaries, and monox is used as a supporter, and the preparing method comprises the steps of adding an alkaline solution A into a reaction kettle, adding a mixed solution of soluble magnesium salt or ferric salt and rare earth metal salt at a constant speed to be subjected to reaction, adjusting pH to 7.5-10 after the reaction is finished, continuing to conduct parallel flowing at a constant speed on the reaction solution and adding soluble nickel salt solution and alkaline solution B into the reaction solution, conducting reaction at the temperature of 65-95 DEG C, adjusting pH to 8-10 after the reaction is over, continuing to stir, filter, and wash deionized water, conducting drying, smashing , and reducing on the obtained catalyst precursor filter cake to obtain the monox-supported nickel base hydrogenation catalyst for oil, wherein the alkaline solution A is a mixed solution prepared from ammonium carbonate and sodium carbonate or sodium hydroxide and deionized water, the alkaline solution B is a mixed solution prepared from sodium silicate solution and sodium carbonate or sodium hydroxide and deionized water. The preparing method of the monox-supported nickel base hydrogenation catalyst for oil is simple in preparing technology, good in repeatability and safe in operation; meanwhile, the obtained monox-supported nickel base hydrogenation catalyst for oil has a high activity, and is convenient to use.