To better cope with extreme precipitation disasters in river basins, a three-dimensional precipitation event identification method was proposed based on the grid aggregation theory. The method involved identification, clustering, and segmentation steps to capture precipitation events and their three-dimensional characteristics. On this basis, a Copula function was used to couple the duration, intensity, and total amount of precipitation, forming a new extreme precipitation index COP. A case analysis of the spatiotemporal dynamic evolution of extreme precipitation was conducted in the Yellow River Basin.The results show that the three-dimensional precipitation event identification method proposed in this paper can effectively capture the evolution process of precipitation events.Compared with the traditional P₉₅ extreme precipitation index, the proposed extreme precipitation index can more accurately capture the spatiotemporal migration patterns of extreme precipitation in the Yellow River Basin and account for the cumulative contribution of weak precipitation events during the development of extreme precipitation, providing a more comprehensive description of the spatiotemporal evolution mechanism of extreme precipitation events.