The invention relates to ultra quick quenching oil and a preparation method thereof. The ultra quick quenching oil comprises the following raw materials in percentage by weight: 80 to 97 percent of refined mineral oil, 1 to 10 percent of cooling catalyst, 1 to 5 percent of antioxidant and 1 to 6 percent of anionic surfactant. The kinematic viscosity of the refined mineral oil at the temperature of 40 DEG C is 6 to 9 mm<2>/s; the cooling catalyst is a mixture of oily phenolic resin and polybutylene; the antioxidant is alkylated diphenylamine; and the anionic surfactant is petroleum sodium sulfonate. The preparation method of the ultra quick quenching oil is simple and convenient; the obtained quenching oil has the advantages of ultra high cooling speed, good thermal oxidation stability, long service life and continuous and stable property retention; little peculiar smell, smog and carbon deposit are produced, and the take-out consumption of a workpiece is low; and after the workpiece is quenched by adopting the quenching oil, the workpiece has the advantages of high and uniform surface hardness, deep quenching layer, low deformation, metallographic structure, good mechanical property and good brightness, the surface of the workpiece does not become black, and the workpiece is easily cleaned.