This invention provides a device and method for diagnosing thermal images, which relates to a thermal imaging device and an applied field of infrared detection. The conventional thermal imaging device is excessively dependent on subjective experience of users to set an analysis area and mode of a thermal image during photographing, causing complicated operation and affecting assessments of thermal images. In the invention, a reference image reflecting morphological characters of a photographed body is superimposed and displayed in an infrared thermal image, and is as a visual reference of the photographed thermal image. The thermal image is diagnosed according to a corresponding analysis area and a specified diagnosis mode, to acquire a diagnosis result. Thereby, the common users can achieve the better photographing level.
