Conversion of carbon dioxide (CO2) into valuable chemicals in gentle conditions is a great challenge in sustainable and energy chemistry. Here we report a CO2-participated polymerization using frustrated Lewis pair (FLP) as the monomer, which allows us to obtain well-defined CO2/FLP alternating copolymers with high molecular weights (∼50000) and quantitative conversions (∼95%), resembling a "click" polymerization of CO2 gas and FLP molecules. In comparison to other CO2-based polymerizations, this method features spontaneity, catalyst-free, and speediness, as well as can realize in ambient temperature (20 °C) and low CO2 pressure conditions (1.0 atm). Moreover, owing to the dynamic covalent bonding between CO2 and FLP unit, such a class of alternating copolymers upon heating can depolymerize into initial monomers and release CO2, which could make them as recyclable smart materials for reversible C1 fixation and release.