With neoated rotifer Brachionus plicatilis BZ]taken as the tested animal, the toxic effect of Cu++ and Zn++ ions on rotifer was examined at 25. The results show that rotifer was very sensitive to Cu++ ion with the 24h LC50s ranging from 14.47 g/L to 21.93 g/L, while rotifer was exposed to Zn++ ion with the 24h LC50s from 3.404 mg/L to 4.549 mg/L under the same experimental conditions.