Abstract: In order to study the effect of the water purification plant, Myriophyllum spicatum L., on feeding the grass carp, the effects of the experimental diets supplemented with different amounts of M. spicatum, including 0 (CK), 5% (M1), 10% (M2), 20% (M3) and 30% (M4) on the growth, muscle quality and safety of grass carp were discussed. The results showed that: the weight gain rate of grass carp in M2 group was the largest (323.40%), the survival rate was the highest (98.45%), and the feeding coefficient was the lowest (1.32). There was no significant difference in the contents of crude protein, crude fat and crude ash in the muscle of grass carp in each treatment group, but the water ratio of the treatment M2 supplemented with 10% M. spicatum powder (M2) was significantly lower than that of the control treatment. After the experiment, the heavy metals (such as total mercury, cadmium, chromium, lead and total arsenic), volatile base nitrogen, enrofloxacin and florfenicol in grass carp were in line with GB2736-94 “Hygienic Standard for Freshwater Fish” and GB31650-2019 “Standard for Maximum Residue Limits of Veterinary Drugs in Food”. The results showed that adding no more than 10% of M. spicatum powder in the diet could promote the growth of grass carp and improve the quality of their muscles.