The invention provides a titanium diboride-titanium dioxide-based high-temperature solar energy absorbing coating and a preparation method thereof. The titanium diboride-titanium dioxide-based high-temperature solar energy absorbing coating is deposited on a substrate of a solar energy heat collecting element and sequentially comprises an infrared reflecting layer, an absorbing layer and an anti-reflecting layer upwards from the surface of the substrate; and the infrared reflecting layer is constituted by a metal tungsten thin film, the absorbing layer is constituted by a composite ceramic thin film prepared from titanium diboride and titanium dioxide, and the anti-reflecting layer is constituted by aluminum oxide. The titanium diboride-titanium dioxide-based high-temperature solar energyabsorbing coating has the excellent optical property and good heat stability, is simple in preparation process, and is suitable for industrial production and application.