As an important infrastructure in transportation, aerospace, unmanned systems and other fields, the performance of Global Navigation Satellite System (GNSS) is directly related to the reliability of positioning and navigation services. This paper takes the measured data from monitoring stations as the research object and proposes a set of methods on the analysis and evaluation of GNSS navigation performance, centering on four core indicators: accuracy, integrity, continuity and availability. Based on this, the advantages and shortcomings of the system in different dimensions are summarized, and corresponding improvement ideas are proposed. The research in this paper not only provides technical support for the application of multi-system fusion and augmentation technology, but also provides a reference basis for the reliable use of GNSS in safety-critical scenarios.