Through a series of simulation and experimental observation， the damage process of 1 μm high power continuous laser on 304 stainless steel was deeply analyzed， and the influence of different power density， material thickness and thermal coupling on the material burn-through time and its change rule were emphatically discussed. The results show that with the increase of stainless steel thickness， the influence of thermal stress and temperature gradient on material deformation and crack formation is intensified， resulting in the increase of laser power density and time required for penetration. The contribution of thermal stress further accelerates the failure process of the material， especially at higher power density， thermal deformation and stress concentration significantly affect the mechanical properties of the material. As a result， there are significant differences in the penetration damage threshold of 304 stainless steel with a thickness of 0.5-2 mm under high power continuous laser irradiation. Finally， the functional relationship between laser irradiation time and material thickness and breakdown threshold is obtained through numerical analysis and data fitting， so as to achieve quantitative evaluation of the penetration and damage characteristics of 304 stainless steel with high power continuous laser.