The rainfall station network is a primary source of rainfall data, and its efficient design and optimization are crucial. This research focuses on the Minjiang Basin, analyzing the existing network of 209 rainfall stations using the Kagan method. Data from these stations, covering the period from 2010 to 2019, were examined at annual, monthly, and daily time scales to determine the optimal number of stations required for the basin. Additionally, the spatial distribution of the rainfall stations was optimized by constructing the Kagan triangular network. The findings indicate the following: (1) the current network of 209 stations in the Minjiang Basin can be reduced to 118 stations; (2) the Kagan method is effective for optimizing the rainfall station network, providing a solid foundation for future network improvements in the basin.