Copper is an essential element required for normal physiological function of human body. Disruption of copper homeostasis has been associated with the development of cardiovascular diseases. As a redox-active metal, the over-accumulation or deficiency of copper in the body may lead to increased oxidative stress and cause dysfunction of many copper-dependent enzymes. Although a number of copper-binding proteins have been recognised, how this metal regulates the cardiovascular function is still largely unknown. Here we tested the effects of cupric ion (Cu2+) on the canonical (TRPC) and melastatin transient receptor potential 2 (TRPM2) channels. Patch-clamp technique was used to record the currents in HEK293 cells overexpressing TRPC3/4/5/6 and TRPM2 channels. We found that Cu2+ potently activated TRPC4 and TRPC5 channels at micromolar level, but had no stimulatory effect on TRPC3, TRPC6 and TRPM2 channels. In contrast, Cu2+ showed dramatic inhibition on TRPM2 channels activated by intracellular ADP-ribose. The microdomains responsible for the activation of TRPC4/5 or inhibition of TRPM2 channels by Cu2+ were found to be localised at the cell surface, since intracellular application of Cu2+ had no influence on the channel activities. However, the mechanism for the stimulation of TRPC4/5 channels by Cu2+ seems different from that by lanthanides, because the TRPC4 mutant with negatively charged glutamic acid residues replaced by neutral glutamines in the outer pore region can still be activated by Cu2+, but not by gadolinium (Gd3+). We conclude that copper plays an important role in cellular Ca2+ signaling by targeting to multiple cation channels and differentially regulating their activities.