Abstract: In the high power laser system, surface impurities and nodule defects are the key factors causing laser-induced damage of thin film components. The influences and variations of surface impurities and nodule defects on the laser-induced damage of thin film components for different irradiation time and power density were analyzed by establishing the thermal analysis model of thin film components irradiated by continuous high power lasers. The results indicate that, when the surface impurities are irradiated by continuous high power lasers, and their size localizes within a certain range, the maximum temperature of the film components increases with the increasing of impurity size, and the large and shallow nodule defect seeds have a more obvious influence on the temperature rise of the film. With the increasing of the power density and the irradiation time, the range of the impurity size in which the surface impurities cause the thermal melting damage of the thin film components increases. Simultaneously, the range of the seed depth and size of the nodule defects causing the thermal melting damage of the thin film components is broaden.