Aiming at the problems and deficiencies in the traditional perimeter alarm system of distributed optical fiber，the basic principles and characteristics of distributed optical fiber perimeter alarm system were analyzed，and its key technologies were discussed，such as optical fiber cable sensing unit based on vibration，micro strain detection and positioning，signal acquisition and processing，signal demodulation etc.The development status of optical fiber perimeter alarm system at home and abroad is also summarized，and the future research direction of perimeter alarm products is pointed out.