It is very meaningful for the detection and imaging of H2S in living systems due to its important role in many biological processes.In this work,a novel fluorescent probe,DHCD was designed and synthesized for the detection of H2S based on an excited state intramolecular proton transfer(ESIPT） fluorophore.The free probe showed relatively weak fluorescence as the protection of the OH group on a 2,4-dinitrophenyl group in the fluorophore blocked the ESIPT process.However,in presence of H2S,the sensing system displayed a remarkable fluorescence enhancement accompanying with a large Stokes shift(~165 nm） due to the recovery of the ESIPT process resulting from the thiolysis of the 2,4-dinitrophenyl ether in probe DHCD triggered by HS-.The detecting mechanism of probe DHCD for H2S was confirmed by high resolution mass spectrometry.In PBS-DMSO buffer(pH 7.45,99∶1,by volume）,the normalized fluorescence intensity increased linearly with the concentration of HS- within the range of 0-10 μmol/L,and the detection limit of the probe DHCD for HS- was calculated to be 0.84 μmol/L.In addition,the synthesized probe had not only a high selectivity to H2S other than other biologically related analytes,but also a high anti interference ability against other coexisting species,which could satisfy the requirements for the selective detection of H2S in real samples from different origins.Most importantly,this probe possessed excellent cell permeation and low toxicity,and could be used for fluorescent imaging of H2S in HeLa cells.It thus provides a promising approach for studying the effects of H2S in biological systems,and exhibits a great potential in biological applications.