Abstract: Gold nano-defects(diameter=50-100 nm, AFM) were embedded in K9 optical glass by ion beam sputtering. The Laser-Induced Damage Threshold (LIDT) under 1-on-1 laser irradiation of the glass were investigated according to ISO 11254-1, respectively. The LIDT was defined as the incident pulse's energy density when the damage probability started to increase from zero (in joules per square centimeter), and it could be obtained by linear extrapolation of the damage probability data to zero damage probability. By analyzing the LIDTs, the LIDTs with optical glass embedded gold nano-defects were decreased from 26.6 J/cm2 to 15.5 J/cm2. Typical damage micrographs of optical glass embedded gold nano-defects were obtained by Nomarski microscope, showing vertical damage morphologies(explosion craters). Through the results of weak absorption(the weak absorption of optical glass embedded gold nano-defects was 47.33 ppm, 13 times to that of bare K9 optical glass), gold nano-defects formed strong absorption centers and caused local high temperature. Through theoretical calculation and simulation,damage mechanisms of optical glass with gold nano-defects under laser irradiation consisted two parts: (1) while in the optical glass embedded gold nano-defects, before the nano-defects boils, thermal stress exceeds the materials' mechanical strength, leading to mechanical damage. (2) If the nano-defects are vaporized, steam pressure intensified the destruction of the material and caused local crack.