Heavy metal pollution in aquatic ecosystems affect microalgae and zooplanktons, alters the biomass and the abundance of species, and promotes interspecies relationships to the predominance of less sensitive species. In this study, the effect of short-term stress of different concentrations of cadmium heavy metal on Chlorella sp. growth and some biochemical parameters have been investigated. Microalgae were treated at different concentrations of cadmium (0, 150, 250 and 350 μm) in the culture medium for 24 hours. The results showed that the content of chlorophyll a photosynthetic pigments, beta-carotene and total protein content decreased significantly. Also, with increasing cadmium concentration, the content of malondialdehyde in the microalgae of Chlorella sp. increased. The activity of giacacol peroxidase, ascorbate peroxidase and superoxide dismutase antioxidant enzymes increased in Chlorella sp. under short-term stress of cadmium. The highest activity of these enzymes was at the concentration of 150 μM cadmium.