The　application　of　perovskite　quantum　dots　(PQDs)　in　biomedical　fields　such　as　bioimaging　and　biosensing　has　been　limited　owing　to　their　instability　in　the　physiological　environment.　Herein,　PQDs　are　innovatively　encapsulated　into　nano-micelles　composed　of　a　polyethylene　glycol-polycaprolactone　(PEG-PCL)　block　copolymer,　which　allows　the　preparation　of　biocompatible　PQDs　(bio-PQDs)　with　excellent　water　resistance.　Due　to　the　benefits　of　extraordinary　water　resistance　and　biocompatibility,　these　bio-PQDs　are　capable　of　real-time　and　long-term　quantitatively　monitoring　the　H2S　level　in　living　cells　as　well　as　in　zebrafish.