Abstract: Bioretention facilities are one of the most widely used green stormwater infrastructures. The current research mainly focuses on the pollutants removal of bioretention facilities on stormwater runoff. However, there is still a lack of systematic research on the characteristics of greenhouse gas (GHG) emissions from bioretention facilities and the impact of facility fillers on GHG emissions. The laboratory column experiments were used to investigate the emission characteristics of CO₂, CH₄ and N₂O in bioretention facilities, and the emission flux, cumulative emission, global warming potential (GWP) and carbon emission reduction effects were evaluated under zeolite, medium sand and fine sand bioretention fillers. The results showed that the filler types had a significant effect on the GHG emission characteristics of bioretention facilities. The average emission fluxes of CO₂ and CH₄ in the bioretention facilities with fine sand as fillers were the lowest, which were 254.85 mg/(m²·h) and 9.06 μg/(m²·h), respectively. The average emission flux of N₂O in bioretention facilities with zeolite as filler was the lowest, which was 7.72 μg/(m²·h). The GWP of bioretention facilities with zeolite, medium sand and fine sand fillers was 472.83, 213.96 and 137.60 kg/hm² (in terms of CO₂), respectively. In terms of carbon emission reduction, the bioretention facilities could mitigate emissions by reducing COD in rainwater runoff. The bioretention with the three types of fillers could reduce CO₂ emissions by 0.051 7 kg (zeolite), 0.050 6 kg (medium sand) and 0.050 6 kg (fine sand) in a single rainfall. Considering the reduction of greenhouse gas emissions, runoff volume reduction and runoff pollutants removal, fine sand could be preferred as a filler for bioretention facilities.