Theoretically,it is too difficult to predict the location and width of cracks is concrete structure accurately.Theref ore,monitoring cracks of concrete structure is of great significance.Based on pulse-prepump Brillouin optical time domain analysis (PPP -BOTDA),the principle of distributed optical fiber sen sing technology is discussed. By means of model test,this article studies the feasibility of using this techno logy to identify or monitor cracks in concrete structure,and an empirical model of crack monitoring in concrete struct ure is constructed.The experimental results show that the Brillouin frequency shift will increase linea r by along with the rise of optical fiber temperature,and the temperature coefficient is 0.3754M Hz/℃.According to the peak position of Brillouin frequency shift,the location of the crack can be determined,and the s ize of the peak indicates the width of the crack.When fiber and crack are orthogonal,the strain coefficient is 0.0508MHz/με.