Abstract: In order to prevent the agglomeration of nano-CaCO₃ during storage and usage, and improve its compatibility with polymer materials, a new stable solvent-free nano-like fluid (CaCO₃-KHM) was successfully prepared by grafting long-chain organics, polyether-silanes (KHMs) onto the surface of nano-CaCO₃ with covalent grafting technology, and its rheology behaviors were investigated.The results show that CaCO₃ in the prepared CaCO₃-KHM was cubic, and the organic layer was uniformly encapsulated on the surface of CaCO₃ to form a core-shell structure, and the thickness of the organic layer was about 4 nm.the CaCO₃-KHM show liquid-like properties only after the organic content exceeding 70%.The glass transition temperature of CaCO₃-KHM was -36 ℃ and the melting temperature was 10 ℃ by DSC analysis.Thermal analysis reveals that this type of fluid has good thermal stability with an initial decomposition temperature above 260 ℃.The solvent-free CaCO₃ nanofluids can realize the "liquid-liquid" mixing of inorganic nanoparticles and polymer materials, which is of great significance in the modification of thermosetting resins.