It has the advantages of high absorption (0.86-0.92/AM1.5) and low emittance (no more than 0.08/80degree), which is invented by YinZhiQiang professor of Tsinhua university and used in the civil solar water heaters extensively. Its selective absorption coatings adopts the graded AL-N cermet layer. Its film structure is ALN/AL-N/AL-N/AL-N/AL-N (adhesion) which can work effectively in the 200 degree.