Nanosized lithium orthosilicate sorbent has been prepared by precipitation, and its CO ₂ capture performance has been evaluated. The particle size of the adsorbent is small and uniform, which leads to a significant reduction of the calcination temperature and desorption temperature, thus greatly reducing the process energy consumption. Under optimum calcination temperature, relative higher kinetic absorption capacity, i.e., 17.8% within 5 minutes under volume fraction 12.5% CO ₂ model flue gas stream by absorption⁃desorption cyclic test, has been obtained. Static CO ₂ absorption test at different temperatures were well fitted by the double exponential model, demonstrating the double shell mechanism. The rate⁃determining step, Li diffusion rate from the bulk to the surface, was greatly improved even in low⁃CO ₂⁃concentration model flue gas owing to its nano⁃scale character. Therefore, this study has provided a simple and efficient preparation method for nanosized ceramic sorbents, which is promising for thermo⁃swing fluidized bed process.