Abstract:The reflection spectrometer with optical fibre transmission was designed and used in quantitative analysis. The reflection spectrometry was applied to the determination of reducing sugar in samples based on the reduction reaction of the reducing sugar with Fehling’s reagent. The reduction reaction was carried out in a micro-reaction cell, and the reddish colored Cu2O produced was settled at the bottom of the reaction cell. The reflectance R∞, which is directly proportional to the amount of Cu2O produced, was measured by the reflection spectrometer. The fundamental principle, effect factors, and experimental conditions of the method were discussed. Linear relationship was obtained in the range of 20-120 μg of reducing sugar. The special features of this method were its simplicity in operation, relatively high sensitivity of determination, and the use of small amount of reagent. Satisfactory results were obtained in its application to the analysis of wine and honey samples.