Based on gravity observation data collected in the intersection region of the Xianshuihe-Longmenshan-An'ninghe fault zones from 2015 to 2024, contour maps of gravity field variations are constructed. These maps, together with records of earthquakes with M_S≥5.0 that occurred in Sichuan Province over the same period, are used to analyze gravity field changes. The results show that: (1) gravity variation characteristics in the intersection region from 2015 to 2024 exhibit mid-term precursory significance for strong and major earthquakes in Sichuan, such as the Jiuzhaigou M_S7.0 earthquake and the Luding M_S6.8 earthquake, indicating a distinct "window" effect for the occurrence of such events; (2) prior to the Jiuzhaigou M_S7.0 earthquake, the extent and magnitude of positive gravity change anomalies increased rapidly and then decreased sharply or disappeared after the earthquake outside the intersection region; and (3) prior to the Luding M_S6.8 earthquake, the extent and magnitude of positive gravity change anomalies increased over a period of time and then decreased gradually or disappeared after the earthquake within the intersection region. This study provides reference information for the prediction of earthquakes with M_S≥6.0 in Sichuan Province.