To establish the Qiannian Xiulin (Millennium Forest of Xiong’an) that closely resembles a natural forest and is stable and self-adjusting, this study utilized soil precipitation and soil moisture data from 32 weather stations and the Qiannian Xiulin Regional Observation Station in Xiong’an New Area, Hebei Province. Machine learning and mathematical analysis methods were employed to investigate the change pattern of soil moisture content in the Qiannian Xiulin. The results indicate that the soil moisture content of the Qiannian Xiulin in Xiong’an is significantly influenced by the monsoon climate and exhibits distinct seasonal fluctuations. Specifically, soil moisture content increases slightly after soil thawing from January to March, gradually decreases from March to June, and reaches the lowest point in June. After June, it shows an upward trend, reaching the maximum in August, and then decreases again after September. The relative humidity of the surface soil at a depth of 0–10 cm in Qiannian Xiulin is positively correlated with precipitation, while the change pattern of relative soil humidity and precipitation in 20–30 cm and 30–50 cm soil layers are not obvious. There are differences in the impact of precipitation intensity on relative soil moisture in different soil layers. Significant changes in soil moisture will only occur when the daily precipitation exceeds 20 mm. The soil moisture content at these weather stations is consistent with the field observation data of Qiannian Xiulin. This study provides scientific soil moisture change rules for artificial planting management of the Qiannian Xiulin.

Xiong’an New Area, Qiannian Xiulin (Millennium Forest of Xiong’an), soil moisture content, soil relative humidity, seasonal variation, spatial distribution