The adsorption process of Chlamydomonas reinhardtii to copper oxide nanoparticles(CuO-NPs)and its effect on free metal ion release were studied by batch experiments. The results show that Chlamydomonas reinhardtii has a strong adsorption capacity for CuO-NPs. The adsorption follows the Langmuir and Freundlich isotherm model and the quasi secondary kinetic model. The maximum adsorption capacity of is 128 μg per 10⁶ algal cell. The existence of Chlamydomonas reinhardtii has a significant effect on the release of free metal ions. The low concentration of Chlamydomonas reinhardtii promotes the release of Cu²⁺, while the high concentration of Chlamydomonas reinhardtii inhibits the release of Cu²⁺.