Abstract: The internal cause of changes in the physical and mechanical properties of soil is closely related to the microstructure of the particles. Rheology has been proved to be an effective way to study the viscoelasticity and microstructure stability of soil from the perspective of intergranular forces. The effects of salinity on rheological properties and microstructural stability of pure clay mineral illite were studied by steady-state and dynamic rheological tests. The results show that the samples with different salinities are shear thinning in the steady-state rheological test. When the shear rate is greater than 0.5 s^-1, the Herschel-Bulkley model can describe the flow curves well. When the salt concentration increases from 0 to 1.8 mol/L, the yield stress varies in the range of 1500~3500 Pa and is positively correlated with salinity. The dynamic rheological tests show that the samples with high salinity have higher energy storage modulus, and the elasticity increases with the increase of salinity. Meanwhile, the influence of salinity on viscoelasticity and shear strength parameters increases with the increase of salinity, which contributes to the structural stability of illite.