Since the fluctuation of cellular hydrogen sulfide (H2S) is a very important third endogenously generated gaseous signaling molecule and plays a key role in the development of numerous human disorders, the real-time fluorescence detection of H2S in living systems has attracted plenty of interest during past decade. Although a lot of H2S fluorescent probes have been reported, the relationship between the physiology and pathology of H2S in organelles remains unclear, especially for inflammatory tissue. In this work, by adopting a weakly basic morpholine group as the lysosome-targeting site, a naphthalimide derivative as the signal reporter group and a 4-dinitrobenzene-ether (DNB) as fluorescence signal quencher and H2S-selective recognition moiety, we reported a new lysosome-targeting TP fluorescent probe LyNP-H2S for H2S detection and imaging in living cells and inflamed tissues. The probe LyNP-H2S exhibits very low fluorescence signal in the absence of H2S, and displays a significant 262-fold fluorescence intensity enhancement in the presence of H2S at 540 nm. Moreover, LyNP-H2S has the capability of quantitative detection of H2S at concentrations ranging from 0 to 12.0 μM (limit of detection = 9.8 nM), rapid response, as well as high sensitivity and selectivity toward H2S. Impressively, the results of living cell and inflamed tissues imaging test demonstrate that LyNP-H2S has the potentiality of being an ideal probe for real-time H2S detection in biosystems. Copyright © 2020 Elsevier B.V. All rights reserved.