Abstract: This paper discusses the rheological properties of CaCO₃/UP and CaCO₃-glass(UP systyms respectively in which CaCO₃ has been treated by coupling agents.The results indicate that the dispersion state of CaCO₃ in CaCO₃/UP system will change from a single particle state to aaccumulated group structure gradually,accompanying by the increase of CaCO₃ content.The rheological properties of the system that consists of accumulated group structures can be shown by the formula In η_γ=9.23φ/(1-2.0φ).As to CaCO₃-glass/UP system,its rheological properties ate obviousiy affected by glass fibres,and there exists a loose structure that is mechanically formed between glass fibres.Casson equation can be used to characcterize this system so long as glass fibre content is small,and ý is less than 100 s^-1.It is found that the different molecular structures on coupling agents and their different combination forms on the surface of CaCos will bring about different surface effects on the rheological properties of the systems.