Abstract: To investigate the relationship between extreme precipitation distribution and secondary disasters in the complex terrain, and enhance regional disaster warning capabilities, this study analyzed daily extreme precipitation thresholds, intensity, frequency, and their spatiotemporal distribution patterns using percentile threshold methods based on ERA5 reanalysis data from national and regional meteorological stations in the region of Hunan, Jiangxi, Zhejiang, and Fujian regions in April to September from 1980 to 2020. The research further explored the correlation between extreme precipitation features and secondary disasters under complex terrain conditions. The results are as follows. (1) The daily extreme precipitation thresholds and intensity peaks are concentrated in eastern Fujian coastal areas, Poyang Lake Plain, and western Hunan hills, while low-value zones are located in central Hunan Basin and northern Zhejiang-Fujian hills. Intensity peaks (single-day maximum>200 mm in Poyang Lake Plain) occur in June, with April showing the weakest intensity. (2) The daily extreme precipitation frequency exhibits a spatial distribution pattern of higher occurrences in southeastern regions and fewer in northwestern areas, with mountainous regions significantly higher than plains. The contribution rates to total precipitation show maximum (>35%) in northeastern Fujian coastal areas and minimum (<20%) in Nanling region. The monthly variations reveal that June-July sees highest contribution rates (over 40%) in western Hunan hills and Wuyi Mountain Range, while August-September's high contribution zone lies along Zhejiang-Fujian coast. (3) The extreme precipitation characteristics demonstrate significant correlations with disaster types: frequent-high-intensity events tend to trigger mass landslides/mudslides (coastal Fujian and western Hunan hills), whereas low-frequency-high-intensity events are more likely to cause localized flash floods (Xinjiang River Valley).