Changes in the free zinc(II) concentration are closely related to cell proliferation and apoptosis, especially during the early apoptotic process. In the present paper, we demonstrated that zinc(II) probe FluoZin-3AM owns sensitive properties to distinguish different stages of apoptotic cell (induced by an anticancer agent, etoposide) according to trace intracellular zinc(II) fluorescence flux. When apoptosis in HeLa or K562 cells was artificially induced, FluoZin-3AM selectively and strongly stained apoptotic cells only at early and middle stages, which was attributed to significantly increased free zinc(II) flux during these stages. This conclusion was further verified by comparing it with the conventional apoptosis detector probe Annexin-V-FITC and PI. Furthermore, FluoZin-3AM was found cell permeable to detect the intracellular zinc(II) fluorescence enhancement to threefolds within 120 s with low cytotoxicity when zinc(II) was incorporated into the cell by zinc(II) ionophore pyrithione. All the above implied that monitoring intracellular zinc fluorescence flux was an effective method to distinguish cell apoptosis from necrosis, and FluoZin-3AM was found to be a suitable probe acting alone to fulfill the work.