Abstract: To study the purifying effect of aquatic economic plants on biogas slurry, in this research, purifying experiments of aquatic water spinach were conducted on different concentrations of biogas slurry, the removal efficiency of COD, TN and TP in biogas slurry and the biochemical index were tested, food safety and economic benefits of aquatic water spinach were analyzed. The results showed that aquatic water spinach could be cultivated in high concentration of biogas slurry and had strong purifying effect on biogas slurry; the removal rate of COD reached the highest when aquatic water spinach was cultivated in biogas slurry diluted 40 times, and aquatic water spinach had the best economic benefits when cultivated in biogas slurry diluted 30 times, heavy metal indicators met the green food standards for aquatic vegetables (NY/T 1405—2015). Aquatic water spinach cultivated in biogas slurry could not only make full use of the nutrients in biogas slurry, but also reduce pollutant emissions of pig farm, thus to guarantee food safety and good environmental and economic benefits.