In this study, a novel hybrid nanofluid, composed of a composite core of poly(2-dimethylamino ethyl methacrylate) microgel and silica (PDMAEMA/SiO2) and a shell of polyetheramine (M2070), was fabricated via a combination of inversed emulsion polymerization, biomimetic silicification and grafting onto approach. Firstly, PDMAEMA microgel of ca. 300-nm diameter with good dispersity was prepared in water/cyclohexane system. Subsequently, walnut kernel-structured and solid spherical PDMAEMA/SiO2 composites were fabricated using swollen and contractive PDMAEMA microgel as catalytic template, respectively. Then 3-(2, 3-epoxypropoxy) propyl trimethoxysilane (IU-1560) modified M2070 was grafted on PDMAEMA/SiO2 composites to obtain two kinds of solvent-free PDMAEMA/SiO2@M2070 hybrid nanofluids with core@shell structure. Finally, the CO2 gas adsorption performance of these nanofluids was investigated under different CO2 pressure (0.5-4.5 MPa) at 25 degrees C. The results indicated that nanofluid with walnut kernel-structured core showed more excellent CO2 adsorption capacity than solid spherical one. Moreover, it still displayed good stability over ten adsorption-desorption cycles.