The invention provides a method for rapidly detecting uniformity of thickness of a film in a nondestructive manner by infrared thermal imaging. According to the method, uniform and stable thermal fluxis provided by a heating device to heat a film to be measured, the heated film sends infrared radiation outwards, an infrared camera head receives radiation signals and converts the radiation signalsinto electric signals, and after the electric signals are treated by a rear treatment device, a temperature distribution graph on the surface of the film to be measured is displayed. At a certain specific time, the percentage of temperature change of the surface of the film to be measured equals to the percentage of thickness change. If the temperatures of the surface of the film to be measure donot have difference, it shows that the thickness of the film is uniform. By the method, the uniformity of the thickness of the film can be rapidly detected in a nondestructive manner, and whether thefilm to the measured is conductive or transparent or not is not considered. The method can be used for sealing detection and the like of lithium battery pole pieces and plastic bags.