Using the system of fiber optic sensor in special coherence combined digital image processing setup and recording to moved number and direction of interferometric fringe and physical formula, collecting and processing image signal of vibration state is presented and professional software is studied and strain(time curve under random vibration state is measured after strain (time curve and vibration frequency for stable vibration were measured where they correspond with theory solution in this paper. This research provides a kind of new method for real -time vibration monitoring of structure engineering.