To evaluate ecological runoff regulation in Beijiang River Basin and analyze the temporal and spatial changes of runoff regulation amount, the hydrological process of the basin was simulated based on SWAT model, considering meteorological, hydrological, underlying surface factors, etc. The runoff regulation amount and its economic value were calculated under the condition of vegetation ecosystem in 1980, 2000 and 2015. The results show that in the 2015 land use scenario, the average annual regulative runoff depth of the ecosystem in the basin was -141.2 mm which was worth 39.62 billion yuan, and the regulative ratio was -12.2%. Under the regulation of Ecosystem, the change of runoff depth in the flood season was 1. 8 times of that in the dry season but the regulative proportion in the flood season was smaller. In the flood season, the regulative amount of runoff was mainly concentrated in the pre-rainy season. The regulation of runoff in the upper reaches of the basin was larger than that in the lower reaches. In the 2000 and 2015 land use scenarios, the spatial distribution of regulative runoff depth in the basin were basically the same. But due to the reduction of vegetation coverage and increase of construction land, the regulative amount of runoff in the basin decreased by 0.082 billion m³ and the regulation value decreased by 0.585 billion yuan.