The invention provides hydraulic oil for hoisting machinery and a preparation method thereof. The hydraulic oil is prepared from the following components: polyurethane, natural rubber extract, dioctylphthalate, nano bentonite, modified calcium carbonate, nano titanium dioxide, zircon powder, three types of 32NS hydrogenation basic oil, polyalpha-olefin synthetic oil, algal oil, a viscosity regulator, an extreme pressure anti-wear additive, an antioxidant, polyol, paraffin wax, a de-foaming agent, a Ca-Zn composite thermal stabilizer, a dispersant and a lubricant. The preparation method provided by the invention is simple and feasible and low in production cost; the preparation method is suitable for a mass-production hydraulic oil preparation technology; the prepared hydraulic oil has theadvantages of good anti-wear performance, wetting performance and oxidation stability; the service life of the hydraulic oil and a hydraulic element is prolonged and the working efficiency of the hoisting machinery is improved.