Abstract The fault of the wind turbines happened frequently, which result in the long nonscheduled shutdown time and the great economic loss. Based on the method of spectrum analysis and envelop spectrum analysis, the wind turbine online vibration monitoring system is developed, which can diagnose the fault and damage of the wind turbines mechanical department (the mainshaft、gearbox and generator) effectively and provide the equipment performance report and the reasonable maintenance advice for the field staff. Therefore the field staff can make a reasonable maintenance plan and manage the equipment scientifically, which shortened the nonscheduled shutdown time and improved the availability of the