With development of the optical fiber sensing technology, the distributed optical fiber sensing technology has been used in the structure crack monitoring in recent years, mainly including the quasi-distributed optical fiber sensing technology of fiber Bragg grating, and distributed fiber optic crack sensing technologies such as optical time domain reflectometry, Brillouin optical time domain reflectometry, Brillouin optical time domain analysis, Brillouin optical correlation domain analysis, and the latest high spatial-resolution pulse pre-pump Brillouin optical time domain analysis and differential pulse-width pair Brillouin optical time domain analysis. Based on the applications of these techniques in structural crack monitoring, their respective advantages and disadvantages and applications of distributed fiber optic crack sensing all through the world are summarized. Additionally, mechanics, distorted light signal and experimental researches are analyzed in the distributed optical fiber crack monitoring, and some opinions on the issues are proposed.