Integrating ECOSTRESS and Urban Functional Zones identified via POI and road network data, this study uses an XGBoost-SHAP framework to analyze spatial differentiation and non-linear drivers of nighttime Land Surface Temperature (LST) in Fuzhou’s main urban area. Results indicate: (1) Residential zones are heat sources whereas industrial zones are cold spots. (2) Socio-economic factors of Nighttime Light Intensity(NTL) and Population Density (POP), plus the 3D morphology factor Average Building Height (BH), dominate warming over 2D factors. (3) NTL saturates near 40; POP and BH thresholds are approximately 150 people/ha and 20 m. Findings support zone-specific regulation.