Abstract: In order to study the rheological properties of the Nostoc sphaeroids Kütz polysaccharide,the cultivated-indoor of Nostoc sphaeroids Kütz as raw materials,taking the Nostoc sphaeroids Kütz polysaccharide by water extraction and alcohol precipitation method as the research object. Using MCR-302 type rotary rheometer to investigate the effects of concentration,pH,temperature,V_C and H₂O₂ on the apparent viscosity of polysaccharide solution and explore the dynamic viscoelasticity of polysaccharide solution in scanning frequency range to reflect its rheological properties. The results showed that the content of polysaccharide was 96.95%,the average molecular weight of polysaccharide was 1.324×10⁵ Da,the monosaccharide composition analysis showed that it was composed of arabia,glucos,galactose,xylose,mannose and glucuronic acid. Nostoc sphaeroids Kütz polysaccharide solution was pseudoplastic non-Newtonian fluid with shear thinning properties;The viscosity of Nostoc sphaeroids Kütz polysaccharide solution increased with the increasing concentration. In the range of 20~80℃,the viscosity of polysaccharide solution decreased with the increase of temperature. The viscosity of polysaccharide solution at pH=3.0 or pH=11.0 was lower than pH=7.0. V_C and H₂O₂ could reduce the viscosity of polysaccharide solution. The storage modulus(G')and loss modulus(G″)increased with increasing concentration of Nostoc sphaeroids Kütz polysaccharide solution in scanning frequency 0.1~10 Hz. In addition,Nostoc sphaeroids Kütz polysaccharide had synergistic thickening interaction with hyaluronic acid.