New strategies for highly selective and sensitive detection of highly toxic environmental pollutants are still a pressing need. Here, through Cu2+ metalated porous nanoscale covalent organic framework (NCOF), a novel heterogeneous NCOF fluorescence probe has been synthesized for sensitive and selectivity detection of hydrogen sulfide (H2S). Upon H2S addition, the Cu2+ released from the CuCOF, accompanied by the fluorescence recovered of COF. As far as we know, NCOF has not been reported as fluorescence probe for H2S detection. The as‐prepared nano CuCOF displays an excellent sensitive response to H2S with a detection limit of 10 nM. In addition, such heterogeneous fluorescence probe exhibited high selectivity towards to H2S relative to other thiols and anionic species. Moreover, the detection of H2S was achieved successfully in different actual water samples.