Improving the permeability of fillers to balance their hydrological regulation and pollution removal performance is the key for the bioretention pond in red soil region. In order to change the permeability of red soil, different proportions of river sand were mixed into red soil, and their effects on hydrological regulation and pollution removal of bioretention pond system under different rainfall intensity at different recurrence periods were compared and analyzed. The results show that the surface runoff treatment rate increases with the increase of sediment mixing ratio, the peak reduction rate does not change significantly with the increase of sand mixing ratio, and the peak delay time decreases with the increase of sediment mixing ratio. The removal rate of nitrate increases with the increase of sediment content, but the removal rate of COD decreases with the increase of sediment content, and little effect on the removal rate of ammonia nitrogen and total phosphorus. Considering the effects of hydrological regulation and pollution removal, 20% red loam and 80% river sand are the scientific proportion of fillers for bioretention facilities in red soil area.