Based on the thermodynamic theory of thin-film components, the thermal analysis model of thin-film components continuously radiated by high-power lasers is built up. On this basis, the heat transferring process of the thin-film components from impurities to their surrounding thin-film after the surface impurities absorbing heat is simulated, and the influences of surface cleanliness level and the impurity size on the thermal stress damage of the thin-film components are discussed. The results show that, under the continuous radiation of high-power lasers, the laser-energy-absorption of surface impurities gives rise to the relatively high increase of temperature. And the longer the laser irradiation time and the bigger the power density, the more the temperature of the impurities increases. After absorbing heat, the impurities with and without the reaching of melting points transfer heat to their surrounding thin film by the thermal-conduction and thermal-radiation ways, respectively. The temperature rise of the surface of thin-film components caused by thermal-conduction is obviously higher than that by thermal-radiation. Furthermore, the heat-transfer from impurities to surrounding thin-film results in a non-uniform temperature gradient, which further causes the thermal stress. The thermal stress increases with the increase of the temperature gradient, and the thermal stress damage is more likely to happen if the surface impurities localize within a certain range. In addition, the higher the surface cleanliness level of thin-film components and the more the number of impurities, the more easily the thin-film components are damaged.