[Objective] Against the backdrop of global climate change, precipitation patterns in the Dongting Lake Basin have undergone notable shifts, with increases in both the frequency and intensity of extreme rainfall events. Accurately assessing long-term trends in areal rainfall and deciphering their spatiotemporal evolution are therefore fundamental to improving fine-scale precipitation forecasting, and are critical for rational reservoir operation and flood-drought risk management. This study aims to systematically characterize the climatic baseline, interannual-interdecadal trends, multi-scale periodic oscillations, and spatial differentiation of areal rainfall across the secondary sub-basins of the Dongting Lake Basin, with particular emphasis on clarifying the inter-sub-basin differences in precipitation abundance and deficit and their temporal stability. The findings are intended to fill the existing gap in a comprehensive, multi-dimensional understanding of areal rainfall variability in this basin, and to provide robust scientific support for optimal water resource allocation, coordinated reservoir group operation, and flood-drought early warning and risk mitigation. [Methods] Using monthly precipitation records from 1991 to 2024 collected at 129 national basic meteorological stations distributed across Hunan, Guizhou, Chongqing, Hubei, Jiangxi, and Guangxi within the Dongting Lake Basin, this study first calculated areal rainfall for each secondary sub-basin via the Thiessen polygon weighted average method, and derived climatological metrics including multi-year mean annual areal rainfall and the proportion contributed by the flood season (March-September). Trend analysis was performed using the Mann-Kendall test and Sen's slope estimator, while the Pettitt test was employed to detect potential abrupt change points. Dominant periods were extracted via fast Fourier transform (FFT) for both annual and seasonal series. Spatial clustering of multi-year mean precipitation was assessed using the Getis-Ord Gi* statistic to identify significant hotspots and coldspots.[Results] (1) Multi-year mean annual areal rainfall across the sub-basins ranged from 1323.1 to 1495.4 mm, with the highest value in the Xiangjiang (1495.4 mm) and the lowest in the Yuan River (1323.1 mm), yielding a spatial gradient of 172.3 mm. The flood season (March-September) contributed 75.6%-79.7% of the annual total, indicating a high degree of seasonal concentration—highest in the Lishui (79.7%) and lowest in the Xiangjiang (75.6%). (2) Over the study period, annual areal rainfall exhibited a west-east dipole trend: the western Yuan River showed a slight upward tendency (+3.01 mm/decade), whereas the eastern sub-basins experienced decreasing trends, most pronounced in the Zishui (−44.30 mm/decade), followed by the Lishui (−42.88 mm/decade) and the Dongting Lake area (−38.29 mm/decade), with the Xiangjiang showing the smallest decline (−4.37 mm/decade). None of these trends reached statistical significance (p > 0.05), and the Pettitt test detected no significant abrupt change points. (3) Multi-scale periodic oscillations were evident. At the annual scale, the Xiangjiang, Zishui, and Dongting Lake sub-basins shared a dominant period of 3.8 years, the Lishui exhibited a 4.2-year period (both interannual), while the Yuan River showed a distinct interdecadal period of 17.0 years. Seasonally, spring and summer rainfall displayed purely interannual periodicities across all sub-basins, whereas autumn and winter exhibited mixed signals—the Xiangjiang and Zishui dominated by 2.6-year interannual cycles, and the Dongting Lake, Lishui, and Yuan River by 17.0-year interdecadal cycles. (4) The Getis-Ord Gi* analysis identified four significant hotspots and two significant coldspots. Hotspots were predominantly concentrated in the upper Xiangjiang (within Guangxi), while coldspots were centered in the upper Yuan River (within Guizhou). [Conclusions] This study reveals three salient features of precipitation variability in the Dongting Lake Basin: a west-east dipole trend pattern, the coexistence of interannual and interdecadal periodicities, and a stable spatial dichotomy characterized by wetter conditions in the upper Xiangjiang and drier conditions in the upper Yuan River. These findings fill a critical gap in systematic, multi-dimensional research on areal rainfall dynamics in this basin. The marked heterogeneity among sub-basins underscores the need for region-specific water resource management and differentiated flood-drought response strategies. The results are directly applicable to coordinated reservoir group operation and early warning of extreme hydro-meteorological events. Future work should integrate atmospheric circulation drivers (e.g., ENSO, PDO), reanalysis datasets, and extreme precipitation indices, together with local topographic effects and the seasonal progression of the East Asian monsoon, in a multi-factor attribution framework to further elucidate the mechanisms governing the observed rainfall patterns and their evolution.