To research the relationship among the thermal-stress , strain and interfacial adhesion strength of coating. Thermal-stress and strain of coating were theoretically analyzed, and theoretical model of coating’s thermal-stress and strain formulas were established. The infrared-laser scratch testing indicates that there is an evident break process along the thickness of coating after it was scratched by infrared laser and the position of break point is the critical location where the coating is broken off from substrate. The research results also show that the separate-stress of coating becomes stronger with the coating’s temperature increasing when the coating is scratched by infrared laser. And the separate-stress presentes two-phase process, which further illuminates that the turning point of two-phase process reflects the interfacial adhesion strength of coating.