Abstract: The complex terrain area formed by the eastern slope of the Qinghai-Xizang Plateau and the Sichuan Basin is one of the key regions with frequent convective initiation (CI). Based on high spatiotemporal resolution radar composite reflectivity and ground precipitation observation data from April to September of 2024—2025, this study proposes an objective method for identifying CI events using a target-oriented area overlap method. We conduct statistical analysis of the eastern plateau slope and the Sichuan Basin, classify CI events into precipitation-producing and non-precipitation types, and systematically reveal their spatiotemporal distribution and precipitation conversion features. The results show that: (1) During the study period, a total of 666,715 CI events over the study area were identified, with an average of 3643 events per day, indicating extremely active CI activities. The diurnal variation presented a bimodal pattern, with the main peak occurring from early morning to dawn (04:00—09:00 Beijing Time), and the secondary peak occurring from evening to night ( 18:00—21:00 Beijing Time), corresponding to the dominant mechanisms of dynamic lifting and thermal forcing. In spring (April), the single peak type changed to a bimodal type in the warm season (May–September), reflecting the regulatory effect of seasonal transitions on the CI triggering mechanisms. (2) The spatial distribution of CI is closely coupled with the terrain and large-scale circulation. High-occurrence zones are distributed in a belt along the steep terrain transition from the plateau to the basin, and their spatial patterns vary with seasons. In spring, the pattern is "strong in the south and weak in the north" in the southern basin. In summer, it coincides with the western boundary of the Western Pacific Subtropical High. In autumn, with the eastward retreat of the Western Pacific Subtropical High, these high-occurrence zones shift eastward with weakened frequency. (3) The precipitation probability of CI on the eastern slope of the Qinghai-Xizang Plateau and the Sichuan Basin was relatively high, exceeding 70% in all months. The highest precipitation probability (94%) occurred in September (West China Autumn Rain period), and the lowest (approximately 72%) in August. The size of precipitation-type CI showed a unimodal distribution, with the peak located near 8 grid points (approximately 64 km²) and 55% of events concentrated in the moderate-size range of 4 to 13 grid points. The research results clarify that CI activities over the eastern slope of the Qinghai-Xizang Plateau and the Sichuan Basin are jointly modulated by terrain, thermal conditions, and circulation, characterized by high occurrence frequency, seasonal migration, and a high precipitation conversion probability. These findings provide scientific support for improving regional convective parameterization schemes and optimizing monitoring and warning thresholds, thereby enhancing the warning capability for short-duration heavy precipitation over the eastern Qinghai-Xizang Plateau.