The polysaccharide of soybean hull （SHP） was a high molecular weight acidic polysaccharide isolated and purified from soybean hull. The atomic force microscopy （AFM） was used to observe the apparent morphology on the surface of solution-mica for exploring the advanced conformational characteristics of polysaccharides， and verified by rheology. The results showed that the mass concentration and ionic strength significantly affected the AFM imaging of SHP， and the images of molecular aggregation behavior of different morphological polysaccharides were obtained. The interaction between polysaccharides was weakened as the concentration decreased. The conformation of polysaccharides gradually dispersed from densely packed strip-like structures into branched， single- and double-stranded structures in aqueous solution， and a cross-linked gel network structure into a short spiral-like structure in 0.5 mol/L KCl solution. The effects of ionic strength on SHP were reflected in the tightness of polysaccharide， and the conformation transformed from a stretched flexible long chain to a helical rigid short chain. By static rheological measurement of SHP solution， it was verified that the addition of KCl led to the cross-linking of polysaccharides chains to form a network structure， and the solution system gradually changed from a fluid state to a weak gel state.