A symmetrical N 2 O 2 -tetradentate dioxime chemical sensor H 2 L was synthesized for the first time. The sensor H 2 L can identify S 2- ion with dual channels of fluorescence-ultraviolet spectra, and through the calculation of binding constant and detection limit of L-S system, it was showed that H 2 L can detect S 2- ion with high efficiency and specificity. pH response experiments were carried out on L-S system and H 2 L to explore the pH range recognized by them. The recognition mechanism was determined by 1 H NMR titration experiment. At the same time, a new method of macro recognition by means of naked eye recognition (under natural light and ultraviolet light of 365 nm) and filter paper recognition was developed. The practical application of the sensor H 2 L to detect H 2 S was evaluated in actual water samples and identification experiment of H 2 S.