The permeability-controllable potentiometric fluorescent probes that can visually discriminate near-zero and normal situations of cell membrane potential were reported for the first time. Different from traditional potentiometric probes that utilize fluorescence intensity to reflect membrane potential, CQ12 and CP12 have different localizations under the two situations of cell membrane potential. Thus, the two situations can be point-to-point indicated by two fluorescent images with an obvious difference, avoiding complex operations and calibration of conventional methods.