The invention provides a liquid coolant for cinema projectors, and a preparation method thereof. The liquid coolant comprises glycol, a buffering agent, water, an anticorrosive agent, a passivating agent, an antifoaming agent, a pH value adjusting agent and a light absorbent. The liquid coolant has the advantages of wide working temperature range, good heat transfer performance, small corrosion, good light stability and certain light absorption performance, and can meet cooling requirements of the cinema projectors.