Sulfites (HSO3-) are used as preservatives and additives in many foods and medicines. However, a high sulfite concentration can cause asthma attacks and even breathing difficulties. Sulfites can also accumulate from the environment into the body, so it is necessary to develop a probe capable of detecting SO2 in the environment and in organisms. A multifunctional sensor, SO-2, based on levulinic acid was designed and synthesized. SO-2 showed an excellent response to SO2 with a detection limit of 2.0 × 10-8 M and a fast response equilibrium time (within 10 min), which indicated that the probe could detect SO2 with high sensitivity. The probe also successfully traced exogenous bisulfite in cells and was applied to analyze water samples in a natural environment.