Sulfur fumigation has attracted extensive attention as one of the important post-harvest processing methods for some traditional Chinese medicines (TCMs) in the last decade. However, sulfur fumigation has recently emerged as a controversial topic due to its potential detrimental effects on the safety and efficacy of TCMs as some sulfur-fumigated TCMs contain numerous sulfur dioxide derivatives; moreover, high levels of sulfur dioxide derivatives can cause some diseases and dangerous environmental pollution. In this study, a DTCC probe with a fast response time, low limit of detection and a high fluorescence quantum yield was designed and synthesized to detect SO₂ derivatives based on the coumarin-thiophene dye, which was fused with a coumarin moiety and 2-thiophenecarboxaldehyde. The probe DTCC exhibited a fast response time (less than 10 s), satisfactory selectivity for SO₂ derivatives in the presence of other ROS and excellent sensitivity for SO₂ derivatives with a low limit of detection (0.23 μM) as well as a wide linear range (0–100 μM). Furthermore, the probe DTCC was successfully applied in fluorescence imaging in SH-SY5Y neuroblastoma cells with excellent membrane permeability and stability. It was also employed in monitoring the total SO₂ derivatives in several real TCM samples. These results illustrate that the probe DTCC has an excellent capability for monitoring SO₂ derivatives in living cells and real TCM samples.