The invention discloses a method for measuring the thickness of a coating through optical pulse infrared thermal imaging, and relates to a method for measuring the thickness of the coating to solve the problem that a current method for measuring the thickness of the coating is limited by the characteristics of measured materials. The method includes the steps of heating a structural element of the measured coating under two different types of pulse strength through a pulse heating device, collecting thermal image sequences T1(x,y,N) and T2(x,y,N) on the surface of the structural element of the measured coating under the same sampling frequency fs through an infrared thermal imager, subtracting the thermal image sequence T1(x,y,N) from the thermal image sequence T2(x,y,N) to obtain a thermal wave signal delta T which is equal to T2(x,y,N) minus T1(x,y,N), conducting linear fitting on the relationships between thermal wave signals of all pixels and collection frame numbers to obtain a delta T(x,y,N) which is equal to aN plus b, and obtaining the coating thickness ec of the structural element of the measured coating according to a formula and according to the obtained a and the obtained b. The method is used for measuring the coating thickness of the structural element of the measured coating.