Abstract: Climate regulation service is an important component of ecosystem services, and analyzing the driving mechanism of spatial variation of climate regulation services is significant for enhancing regional climate adaptation capabilities. This study constructs a random forest-factorial analysis method to investigate the individual and interactive effects of various factors on the spatial variation of climate regulation service value in the Yangtze River Delta (YRD) region. The factors selected include human activity factors (population, GDP, nighttime light index), meteorological factors (precipitation, evapotranspiration, wind speed), and natural geography factors (elevation, slope, normalized difference vegetation index). Additionally, the spatial response of the YRD region to different risk scenarios is explored. The findings are as follows: (1) Human activity factors, meteorological factors, and natural geography factors explain 11.98%, 6.68%, and 77.38% of the spatial variation in regional climate regulation service value, respectively. (2) Human activity factors and wind speed have negative impacts on climate regulation services, while natural geography factors have positive effects. Precipitation and evapotranspiration exhibit threshold effects, with positively impacting climate regulation service value when the precipitation to be below 1 550.1 mm and evapotranspiration to be below 953.4 mm, and negatively impacting it when these thresholds are exceeded. (3) Interaction effects between factors contribute 3.33% to spatial variation, with the top three contributing interaction terms being between precipitation and evapotranspiration, precipitation and slope, and elevation and slope. (4) Southern Anhui and Zhejiang exhibit high climate regulation service value with complex terrain; these areas are dominated by important ecological function zones, natural protection areas, and ecological protection redlines, making them more susceptible to risk disturbances. It is recommended to strengthen ecosystem protection and rationally limit human activities to maintain climate regulation service function in these areas.