According to the phenomena of interface cracking and falling off of protective coatings caused by different thermophysical parameters between protective coatings and aluminum alloy in the process of laser engraving, a two-dimensional finite element model of multi layer materials was established based on the thermal stress coupling analysis method. The pulsed laser was loaded on the surface of protective coatings in the form of Gaussian distributed heat flux. The stress distribution nephogram of aluminum alloy matrix and the evolution law of kerf morphology of protective coatings under the action of thermal stress with different laser processing parameters were obtained by calculation. The effects of laser power, scanning speed, and repetition frequency on temperature field, stress field, engraving morphology, and stress displacement were compared and analyzed, respectively. The results show that when the parameters are selected as power 60 W, scanning speed 10 m/min and repetition frequency 100 kHz, the influence on temperature field, stress field, etching morphology, and stress displacement is minimal. The research of this paper has great reference significance for the practical application of laser engraving in chemical milling, and provides a direction for the process optimization of laser engraving.