When two beams of pump light are injected into both ends of the polarization maintaining optical fiber at the same polarization direction, Brillouin scattering will be produced and coherent acoustic field will be stimulated. The acoustic field will modulate the refractive index of the medium, which is the Brillouin dynamic grating. The dynamic grating can realize high precision and distributed measurement of temperature and strain, and simultaneous sensing of multi-parameter as well, and it presents the advantages of reading and writing separation, adjustable spectrum and so on. The generation principles of Brillouin scattering and Brillouin dynamic grating are introduced in detail, and the application advantages of Brillouin dynamic grating in fiber sensing are analyzed. In this paper, the applications of Brillouin dynamic grating in Brillouin optical coherence domain and Brillouin optical time domain are reviewed in detail, and the disadvantages and improvements are pointed out. Finally, the developments of Brillouin dynamic grating in distributed sensing technology are summarized and prospected.