Disclosed is a carbon-dioxide-responsive self-thickening intelligent fluid based on supramolecular self-assembly, which comprises a Gemini surfactant, a single-chain amide molecule having a tertiary amine head group and water, wherein the Gemini surfactant and the single-chain amide molecule are self-assembled to form a vesicle structure dispersed in water, with a hydrophilic head group being located outside and a hydrophobic tail group located inside. The method for preparing the carbon-dioxide-responsive self-thickening intelligent fluid of the present invention is simple, the injection viscosity is low, and the fluid is converted into a gel when encountering carbon dioxide, so that the viscosity is greatly increased.