The invention discloses an anhydrous coolant and a preparation method thereof. The anhydrous coolant comprises raw materials in parts by weight as follows: 1,000 parts of propylene glycol, 2.4-2.6 parts of an acidic preservative, 1.5-1.7 parts of borax, 1.4-1.6 parts of sodium nitrite, 1.4-1.6 parts of triethanolamine, 0.2-0.4 parts of benzotriazole, 0.05-0.15 parts of a defoaming agent, 5-7 parts of a bittering agent and 0.009-0.011 parts of a pigment. All components of the anhydrous coolant supplement one another and cooperate with one another to have the synergistic effect, the anhydrous coolant has the excellent performance and the wide adaptability, can be perfectly compatible with a hydrous coolant left during replacement of the coolant, enables an engine cooling system to work in a non-pressure or micro-pressure environment, can play a noise reduction role in an engine and cannot age and damage rubber pipelines in advance, so that usage and maintenance costs are reduced, and the service life of the engine is greatly prolonged. Besides, no water exists, so that propylene glycol cannot be acidic at the high temperature, the service life can be prolonged, frequent replacement is not required, the more environment-friendly effect is realized, and the long-term comprehensive cost performance is particularly high.