The Automatic Dependent Surveillance-Broadcast (ADS-B) message contained information such as geometric altitude, barometric altitude, and altitude quality indicators. Analyzing and summarizing the characteristics and correlation of these information can provide guidance and suggestions for further application in air traffic management (ATM). Analysis and optimization of existing aircraft flight altitude data sources are of great significance to ensure flight safety. Based on the ADS-B data of a ground station in a certain area of China, the method, advantages, disadvantages, and availability of the geometric and barometric altitude were analyzed, and the trends of the geometric and barometric altitude and height difference based on the flight phase were studied. The correlation between the ADS-B height quality index parameters and the height difference was summarized. The results show that the absolute difference between the geometric and barometric altitudes of the 664 sample airplanes ranges from 0 m to 284.074 m, with an average of 154.838 m, and only 1.204% of the altitude deviation is less than 74.676 m. Therefore, it is very important for aviation safety to analyze and summarize the correlation and variation law of aviation altitude data.