Porous liquids are an expanding class of material that has huge potential in gas separation and gas adsorption. Pore size has a dramatic influence on the gas adsorption of porous liquids. In this article, we chose hollow silica nanoparticles as cores, 3‐(trihydroxysilyl)‐1‐propanesulfonic acid (SIT) as corona, and inexpensive industrial reagent polyether amine (M2070) as canopy to obtain a new type of porous liquids. Hollow silica nanospheres with different pore sizes were chosen to investigate the influence of porosity size on CO₂ adsorption capacity of porous liquids. Their chemical structure, morphology, thermal behavior and possible adsorption mechanism are discussed in detail. It was proved that with similar grafting density, porous liquid that has bigger pore size possesses a better CO₂ adsorption capacity (2.182 mmol g⁻¹ under 2.5 MPa at 298 K). More than that, this article demonstrates a more facile and low‐cost method to obtain porous liquids with good CO₂ adsorption capacity, recyclability, and huge variability.