Based on site vibration test, the paper analyzed the vibration law of offshore wind power structure in process of unit start and stop.The data show that the vibration amplitude of wind power structure in different work conditions is larger than that in normal running of unit.The range of variation is from 11.23% to 58.45% in start process. The amplitude range is from -25.73% to 387.33% compared with that in normal operation in stop process. It used STD method to recognize the first frequency of wind and power structure that is 0.33Hz. At the same time, the paper carried on the analysis of oscillation range of tower. The result showed that wind and power structure can meet the requirement of structure safety.