Sulfonamides (SAs) are the most common and bio-refractory antibiotics detected in surface water systems, which cause long-term toxic effects on aquatic organisms. This study used the combination of a BiVO photocatalyst and freshwater micro-green alga (Dictyosphaerium sp.) to remove sulfadiazine (SD) and sulfamethazine (SM2) at an initial concentration of 5 mg/L (1:1 v/v) for 7 days. We set up three gradient concentrations of BiVO (0.5, 1 and 2 g/L) combined with the same concentration (80 mg/L) of Dictyosphaerium sp. and then prepared corresponding concentrations of pure BiVO and pure microalgae as controls. We evaluated the ability of BiVO and Dictyosphaerium sp. combined technology to remove SAs by observing the removal efficiency of antibiotics and explained the degradation mechanism of antibiotics and the key role of microalgae by studying the changes of reactive oxygen species (ROS) and inorganic ions (nitrogen, sulfur). The results showed that the degradation rate of these two SAs in the 0.5 g/L BiVO –algae group could reach >96% within 7 d, which was higher than that in the 2 g/L BiVO group (93%) and the algae group (28%). The increased degradation efficiency of SAs in BiVO and microalgae systems was mainly due to the increased amount of ROS. Meanwhile, more SAs were degraded to inorganic compounds such as NH-N, NO-N and SO-S under ROS stress. It was found that microalgae can absorb the degradation products of antibiotics such as NH-N for their own growth, thereby reducing the toxicity of antibiotic by-products. In addition, BiVO had no damaging effect on the autofluorescence intensity of the microalgae. Our study provides an efficient and eco-economic approach to remove antibiotics using visible-light irradiation in aquatic environments and provides new insights into the biological removal of other antibiotic contaminants in aquatic environments.