Effects of the widely used herbicide diuron on growth of the freshwater green alga, Pseudokirchneriella subcapitata, were investigated in C medium with different nitrate （15, 150 or 1501 μM） or phosphate （1.6, 16.3 or 163 μM） levels at three water temperatures （10, 20 and 30°C） for 144 h. Growth was inhibited by 16 μg L^–1 diuron in all cases. Results from generalized linear model （GLM） analysis showed that the growth inhibition rate by diuron treatment was significantly decreased by increased temperature and decreased nutrient levels. Our result indicated that diuron toxicity may decrease under conditions of high temperature and low nutrients. Therefore, nutrient levels at different water temperatures should be considered in risk assessments to learn the actual impact of diuron in real environmental conditions.