In order to study the physiological responses of the algae Caulerpa sertularoides f. Longipes to heavy metal (Cu2+, Pb2+, Cd2+) stress, constant-temperature illuminating cultivation method has been adopted to explore the influence of the stress from Cu2+, Pb2+ and Cd2+ on the specific growth rate (SGR), content of soluble protein, chlorophyll-a (Chl-a), glutathione-S-transferase (GST) and superoxide dismutase (SOD) of the algae. The results show that stress of the three kinds of heavy metal ions affects the normal growth of the algae; SGR showed negative growth; soluble protein and Chl-a contents decreased when the content of heavy metal ions increased; the influence of Cu2+ was most obvious. The inhibition ability of heavy metals on the growth of algae was as follows: Cu2+>Pb2+>Cd2+. Both the SOD and GST contents, under the influence of the three heavy metal ions, increased first and then declined; the peak effect on the SOD concentration appeared when the concentration of Cd2+was 5mg/L, but in other treatment groups the peak effect appeared at the concentration of 2.50mg/L. This study will provide a scientific basis for the study on the mechanism of heavy metal stress to Caulerpa sertularoides f. Longipes.