The current invention has provided a method for detecting, in a noninvasive in-vivo manner, UV-induced skin damage and a detection device thereof. After irradiated by ultraviolet light, the autofluorescence is generated at the wavelength ranging from 490 nm to 640 nm under the skin, following the excitement of laser having a wavelength ranging from 440 nm to 510 nm, wherein the changes of the autofluorescence intensity at the wavelength of 490-640 nm is positively correlated with the skin damages.