Fiber Bragg grating sensors can directly measure physical quantities such as temperature and strain. Since the wavelength of the fiber Bragg grating is sensitive to both temperature and strain simultaneously, that is, both temperature and strain cause the coupling wavelength of the fiber Bragg grating to shift simultaneously, it is impossible to distinguish between temperature and strain by measuring the shift of the coupling wavelength of the fiber Bragg grating. Therefore, solving the problem of cross-sensitivity and achieving the differentiated measurement of temperature and stress are the prerequisites for the practical application of sensors. The differential measurement of temperature and stress is achieved by determining the changes in stress and temperature through certain techniques. The basic principle of these technologies is to form a dual-grating temperature and strain sensor by using two or two segments of fiber Bragg gratings with different temperature and strain response sensitivities. By determining the temperature and strain response sensitivity coefficients of the two fiber Bragg gratings, the temperature and strain can be solved using two binary linear equations. The classification of measurement techniques can be roughly divided into two categories, namely multi-fiber grating measurement and single-fiber grating measurement.