An innovative and simplified method to characterize the chemical composition of the residual sulphite deposits on dried day lily using scanning electron microscopy- energy dispersive X-ray spectrometer (SEM-EDS) was developed in this study. Granular deposits were observed by SEM on the surface of dried day lily overdosed with sulphiting agents. Laboratory scale model studies showed that soaking in 3% sodium bisulphite without subsequent washing may lead to the accumulation and precipitation of sodium bisulphite crystals. EDS analysis indicated that these deposits are sodium bisulphite. A strong correlation (R2 = 0.8994) was obtained between Sulfur/Carbon ratio calculated from SEM-EDS data and sulfur dioxide concentration determined by modified Monier-Williams method in day lily samples without crystals on the surface.