The partial replacement of Portland cement by solid waste to prepare a close-packing composite cementitious material not only is an efficient way both for the low-carbon development of cement and concrete industry and for the improved performance of binder, and the gradation of cementitious material is an important factor affecting the rheological properties of the mixing. This paper investigates the modulus of a close packing model on the rheological properties of paste. The results show that with the increase of distribution modulus, the yield stress and plastic viscosity of different composite pastes show inconsistent changes. The rheological properties of pastes are correlated with its packing density to a certain extent while the water film thickness is a key factor to explain the influence of modulus on the rheological properties. As the water film thickness increases, both the yield stress and plastic viscosity show a power-law decrease trend. This effect can be represented by the simplified YODEL model and Ahmadah model.