Abstract: Monolayer SiO2 optical thin films(refractive is 1.46) and SiNx optical thin films(refractive is 1.84) with different thicknesses were prepared by the plasma enhanced chemical vapor deposition (PECVD) technology on BK7 substrates,their laser-induced damage thresholds(LIDT) were measured,and the relationship between the monolayer optical thin film and its laser-induced damage properties was analyzed.The results indicate that monolayer SiO2 thin films prepared by PECVD technology have high LIDT,when the optical thickness of films is between o/4 and o/2, LIDT has the maximum 27.9 J/cm2 when the optical thickness is 433 nm,LIDT has the minimum 21.7 J/cm2 when the optical thickness is 350 nm. The LIDT of monolayer SiNx thin films decrease with the increase OF optical thickness , LIDT has the maximum 29.3 J/cm2 when the optical thickness is o/4,LIDT has the minimum 4.9 J/cm2 when the optical thickness is o/2.