Hypochlorite is widely used in the disinfection products for hard surface and water, and the detection of hypochlorite is very important. The ratiometric fluorescent probes have many advantages, such as high sensitivity, fast response, good selectivity and real-time monitoring, and the ratiometric probes could elim-inate the background interference well. Therefore, a ratiometric fluorescent probe ZN1 for hypochlorite was synthesized in this work. This probe possesses high speed, great sensitivity, and nice selectivity for de-tection of hypochlorite ions, and it has been successfully applied for the detection of hypochlorite in real water samples. Moreover, the sensing mechanism of the probe was studied by MS and NMR spectra.