Aiming at the problems of infrared quantitative detection of thermal barrier coating structures, the LM recognition algorithm based on pulse phase was put forward. The transient thermal model of thermal barrier coating structures was established in an axisymmetric cylindrical coordinate in view of the research problem. The surface temperature field of the research model was calculated by the finite volume method. Then the phase distribution of the inspection surface was obtained through a fast Fourier transform. The impacts of parameters to be detected on the phase difference of the inspection surface were analyzed. Taking the phase as identification condition, the quantitative identification of coating thickness and material inner defects was conducted by using LM inversion algorithm. The effectiveness of LM identification method on the basis of phase detection was evidenced by the numerical experiment results.