Hydrosulphite (HSO 3− ), as a common and important chemical reagent, is widely used in everyday life, however excessive use and abuse of HSO 3 − can cause potential harmful effects on the environment and in biological health. In this paper, we describe the design and preparation of a colorimetric and ratiometric fluorescence probe for the visual detection of HSO 3 − (excitation wavelengths were, respectively, 336 nm and 520 nm). This method showed some advantages including simple preparation, high selectivity, fast response, and significant colour and fluorescence ratio (F 450 /F 594 ) changes in the presence of HSO 3 − . In addition, this probe was used successfully for the detection of HSO 3 − in real water samples and showed a good recovery rate range. K E Y W O R D S colorimetric and ratiometric detection, fluorescent probe, HSO 3 − , water sample 1 | INTRODUCTION Hydrosulphite (HSO 3 −) has been widely used as a bleaching agent for taffeta, and reducing agent in dyestuffs, papermaking, leather making, chemical synthesis, and other industries, and as a raw material for medicine, preservatives and antioxidants for food, and electroplating additives. [1][2][3][4][5] However, excess concentrations of HSO 3 − can cause potential harm to water safety and human health. For instance, exposure to HSO 3 − can cause skin and corneal damages [6,7] and drinking water containing superfluous HSO 3 − can also cause nausea, abdominal pain, diarrhoea, circulatory failure, and central nervous system depression. [8][9][10][11][12][13] In addition, both forms are derivatives of the toxic