The invention discloses a method and device used for detecting radial drifting of a rotator based on electrostatic sensor arrays and belongs to the technical scope of radial vibration detection of rotary machinery. The device used for detecting radial drifting of the rotator comprises one or more sets of electrostatic senor arrays which are installed on the periphery of the rotator to be detected. According to the method and device used for detecting radial drifting of the rotator based on the electrostatic sensor arrays, an electrostatic signal is generated by each electrostatic sensor through electrostatic induction in the operating process of the rotator, each electrostatic signal is amplified and filtered through a signal conditioning unit and is converted through an analog-digital converter, digital signal processing is then carried out on each converted signal in a microprocessor, the electrostatic strength of a plurality of sets electrostatic signals acquired are calculated and analyzed, and then information of radial drifting of the rotator is obtained. Compared with an existing electrical vortex sensor or an existing laser displacement sensor, the device used for detecting radial drifting of the rotator by means of the electrostatic sensor arrays has the advantages of being simple in structure, low in cost, convenient to operate and maintain, not prone to influence of environmental conditions and the like.