Abstract: ‍ ‍Ionospheric delay and multipath interference are the main sources of interference for Ground-Based Augmentation Systems （GBAS） and Instrument Landing Systems （ILS）， respectively. On the basis of realizing the time and space alignment of the GBAS and the ILS， the impact of ionospheric storms on GBAS and multipath interference on ILS were analyzed. The motion model of the aircraft precision approach and landing stage was established by deeply analyzing a number of approach and landing flight data collected from the flight simulation software X-Plane. A data fusion method of GBAS and ILS based on improved Sage-Husa adaptive filtering and learning algorithm for variance estimation was introduced. The experimental verification system was built based on the X-Plane and self-developed data acquisition module， and the simulation experiment was carried out in three conditions， which were the GBAS was not affected by ionospheric storm while the ILS was affected by weak multipath interference， the GBAS was affected by ionospheric storm while the ILS was affected by weak multipath interference， and the GBAS was not affected by ionospheric storm while the ILS was affected by multipath interference. The experimental results show that the improved Sage-Husa algorithm can effectively suppress the influence of ionospheric storm on GBAS and the interference of multipath effect on ILS， so that the navigation system combined with GBAS and ILS can provide horizontal and vertical guidance for aircraft to meet the requirements of category I precision approach accuracy under the corresponding interference conditions， and the survivability of precision approach operation is effectively enhanced.