The invention provides a measuring method and system for micrometer-scale temperature distribution of a device on the basis of a fiber lens. The method includes the steps: coating the surface of a to-be-measured device sample with a rare earth film; irradiating laser to the surface of the rare earth film, and collecting two kinds of fluorescent light that is excited by the rare earth film and different in wavelength; separating the two kinds of fluorescent light different in wavelength, and imaging the rare earth film under the different fluorescent light different in wavelength; and demodulating the rare earth film images under the different fluorescent light different in wavelength, calculating an energy ratio of rare earth film image corresponding points under the different fluorescent light different in wavelength, and then obtaining the two-dimensional temperature distribution on the surface of the to-be-measured device sample. The method has the advantages of quick temperature measuring, high precision or the like, and can display the two-dimensional temperature distribution on the surface of a device in real time.