Abstract: ‍ ‍Since satellite signals are very weak and vulnerable to all kinds of intentional and unintentional interference， the Global Navigation Satellite System （GNSS） cannot provide services safely and reliably. The research on GNSS interference monitoring method is of great significance to civil aviation flight safety. Based on the variation characteristics of navigation integrity index in ADS-B data caused by GNSS interference， a multi-level GNSS interference monitoring method is presented. Firstly， statistical analysis is conducted on the Navigation Integrity Category （NIC） of ADS-B data to realize crude monitoring of flights affected by interference. Then， based on the fact that multiple flights will be affected simultaneously in the interference area when the interference occurs， MeanShift clustering method was used to realize the fine monitoring of GNSS interference， and the time and location information corresponding to the start and end of the interference area were extracted. The experimental results are compared with the interference monitoring results obtained from QAR （Quick Access Recorder） data to verify the effectiveness of the proposed method.