The invention relates to an optical element technology, solves the problem that the back surface of a current optical element substrate is easily damaged, and provides an optical element for slowing down or eliminating the damage of the back surface of a laser-induced optical element. The optical element is characterized by comprising a substrate, required film and buffer-layer film, the buffer-layer film is located between the back surface of the substrate and the required film, the absolute value obtained by subtraction of an acoustic impedance value of a material used for the buffer-layer film and an acoustic impedance value of a material used for the substrate is less than the product of an additive value of the acoustic impedance of the substrate and the material and a stress coefficient, the stress coefficient determines a tensile stress threshold value and a shock wave peak value of the element, and the numerical value is equal to the ratio of the tensile stress threshold valueto the shock wave peak value. The optical element has the advantages of slowing down or eliminating the damage of the back surface of the optical element substrate, which is suitable for optical elements.