Selective solar energy absorbing coating

The utility model discloses a solar selective absorbing coating. Three layers are formed on the surface of the substrate of a heat absorbing body from bottom to top, wherein the first layer which is made from a metal Nb film and is an infrared reflective layer with the thickness ranging from 140 nm to 250 nm; the second layer is an absorbing layer made from the compound of Nb and Al2O3 and composed of two sublayers with different volume percentage of metal, the thickness of a first sublayer Nb ranges from 45 nm to 75 nm, and the thickness of a second sublayer Nb ranges from 50 nm to 70 nm; the third layer is an anti-reflective layer composed of an Al2O3 layer with the thickness ranging from 65 nm to 85 nm; the infrared reflective layer is made by the Nb target direct current magnetron sputtering technology; the absorbing layer is made by the Nb target direct current reactive magnetron sputtering technology and the Al target intermediate-frequency twin magnetron sputtering technology, taking O2 as reaction gas; and the anti-reflective layer is made by the Al2O3 target intermediate-frequency twin sputtering technology, taking Ar as sputtering gas.