Abstract: In this research, we cultivated aquatic water spinach under different hydraulic loads of biogas slurry by using the inlet and outlet water dynamic system, and analyzed the purifying effect of biogas slurry and the growth of aquatic water spinach. The results showed that the purifying effect of biogas slurry was the best when the hydraulic load was between 1.1×10-2 and 1.7×10-2 m3/(m2·d), and the removal efficiency of COD, NH4+-N and TP was more than 60%. At the same time, the heavy metals concentration in the edible parts of aquatic water spinach was lower than that stipulated by the Standard of Green Food Aquatic Vegetables (NY/T 1405- 2015). Therefore, aquatic water spinach cultivated under reasonable hydraulic load would effective purifying of waste water from pig farm, and could be used as edible vegetables and green fodder whose safety of food was guaranteed, and recycle some of the nitrogen and phosphorus in biogas slurry to achieve certain economic benefits.