［Objective ］ To study the changes of polysaccharide in the drying process of "one steam and one preparation" of Polygonatum sibiricum.［Methods ］ The slices were steamed by atmospheric pressure water isolation steaming,and then dried by heat pump at 60 ℃.Near infrared spectroscopy (NIR ),hyperspectral imaging (HSI ) and middle and far infrared spectroscopy were used to analyze the characteristic spectra of the drying process of Polygonatum sibiricum,and the changes of polysaccharide during the drying process were studied by combining two -dimensional correlation infrared spectroscopy (2D-IR) analysis method.［Results］ The content of polysaccharide was 3.39% after steam heating for 11 h,and 6.67% after drying for 11 h.The content of polysaccharide showed a gradual increase during the drying process.Through two -dimensional correlation analysis,it was showed that the characteristic functional groups of polysaccharides were constantly changing.And at 1 016 cm-1,the sequence of functional group changes was C —H stretching of —CH2 → stretching and deformation of O —H group in water → stretching vibration of N —H group → combination of O —H stretching and C—O stretching → combination of C —H stretching and C —C stretching → glucopyranoside.HSI technology combined with chemometrics,PLSR was used to establish the spectral prediction model of polysaccharide,and the Rp2 of the model was 0.903.［Conclusion ］ Infrared spectroscopy,HSI technology combined with 2D-IR technology can well monitor the changes of polysaccharide in the drying process of Polygonatum sibiricum.