Abstract: The ability of Myriophyllum spicatum to absorb and accumulate Cu and Zn from pig farm biogas slurry was studied. Hydraulic residence time (HRT) of 20, 40 and 60 d were applied for the plants in the study. It was found that the maximum biomass of the plants in 40 d of HRT reached 1 475.00 g, which was 7.40 times higher than that of control. More importantly, the Cu and Zn accumulations in the plants were 7.66 mg·kg^-1 and 64.18 mg·kg^-1, respectively, which were significantly greater than those in control. The metal removal from the slurry by the plants was at the highest levels when 40 d HRT was applied as well. The reductions on COD, ammonia nitrogen and total phosphorus on the slurry were 92.40%, 92.03% and 74.39%, respectively. After the HRT test the plants had increases of 7.62%-12.57% on organic matters, 30.62%-69.38% on N, 5.88%-12.94% on P, and 3.85%-21.15% on K, as well as contents of 6.76-10.78 mg·kg^-1 of Cu and 77.63-130.60 mg·kg^-1 of Zn. The increases of metal contents met the levels set forth by the national GB26419-2010 and the Agricultural Industry Standard of NY929-2005. Furthermore, the harvested M. spicatum could be used for fodder to effectively avoid the concern of secondary pollution after the biogas slurry purification.