An AR-based supplementary teaching system for guzheng and method thereof, the system includes an AR device, a data processing device and positioning devices for key positions, the data processing device is signal-connected to the AR device, and the positioning devices is installed on the guzheng code of guzheng, the positioning devices corresponds to the guzheng code of guzheng one by one; the AR device is used to obtain real scene data; the data processing device is used to guzheng and the positioning devices identify and generate string distribution data; also used to obtain operation instruction based on user actions, execute the operation instruction and generate virtual data; the AR device is also used to convert all data based on the string distribution data The virtual data and the real scene data are superimposed and displayed.