To investigate the response mechanism of Halamphora veneta (Kützing) Levkov to heavy metal stress, we analyzed the effects of different concentrations of four heavy metal, including Cu²⁺，Hg²⁺，Cd²⁺ and Pb²⁺ treatments on its cell density, chlorophyll a, malondialdehyde content and morphological changes. The results showed that：(1) low concentration of heavy metal treatment promoted the growth of H. veneta (Kützing) Levkov, while high concentration of heavy metal inhibited the growth of H. veneta (Kützing) Levkov. (2) The results of chlorophyll a showed that the H. veneta (Kützing) Levkov was sensitive to low concentration of Cu²⁺, Hg²⁺, Cd²⁺ and Pb²⁺, thus the chlorophyll a content of diatoms could be an effective index for the heavy metal monitor. (3) It is showed that the effect of low concentration of Cu²⁺，Hg²⁺，Cd²⁺ and Pb²⁺ on the malondialdehyde (MDA) content in H. veneta (Kützing) Levkov was not obvious, while the content of MDA in the H. veneta (Kützing) Levkov was promoted by the high concentration of heavy metal. (4) The morphological changes of the cells showed that Cu²⁺, Cd²⁺and Pb²⁺ treatment did not cause obvious deformation of H. veneta (Kützing) Levkov, and Hg²⁺ treatment could cause the expansion and deformity of the cells. The above results showed that the H. veneta (Kützing) Levkov possess tolerance mechanism for heavy metal stress, meanwhile, its chlorophyll a content and morphological changes could be used as the water monitoring index for heavy metal pollution.