Bioretention facilities (BRFs) are critical components of Sponge City initiatives in China, yet their performance is highly influenced by regional soil characteristics and temporal pedogenic processes. This study systematically analyzed 61 young BRFs (2-66 months old) across 14 cities in China, representing seven distinct topographic regions. Soil properties, including particle size distribution and organic matter content (OM%), were evaluated at different depths (0-30 cm) and locations -specifically the forebay (inflow section where runoff initially enters and sediments accumulate) and the center (central bioretention media zone representing the primary filtration area) to assess spatiotemporal variations. Results revealed significant regional differences in soil composition, with sandy loam dominating high-rainfall areas (e.g., Southern China) and silty loam prevalent in alluvial plains (e.g., Huang-Huai-Hai Plain). Temporal analysis identified four operational phases-Early Deployment (ED), Performance Optimization (PO), Maintenance-Required (MR), and Aging Infrastructure (AI)-each exhibiting unique soil evolution patterns. Fine particle accumulation increased with system age, particularly in surface layers (0-10 cm), while OM% varied regionally, peaking in the Yunnan-Guizhou Plateau (9.10-12.77 %) and declining in the Loess Plateau (1.55-2.24 %). These findings underscore the need for region-specific BRF designs and age-dependent maintenance strategies to optimize hydrological performance and pollutant removal. The study provides evidence-based guidelines for adapting BRF construction and upkeep to China's diverse environmental conditions, supporting sustainable urban stormwater management.