Following the mechanism of seriesparallel reaction in CO2 absorption process, the intrinsic kinetic equation was established. A macroscopic kinetic equation of CO2 absorption reaction was established based on the theory of double membrane diffusion. Considering the noneideal solution, the concentration effect in the rate equation was corrected differently to obtain eight correction models. Through the orthogonal experiment design, the experimental factors were reaction temperature, initial concentration of potassium carbonate, reaction time and mixture of methane and carbon dioxide, and the level of each factor was 3. The experimental data were measured in a doubledrive reactor and the model parameters were estimated. The residual values of each model were calculated respectively. The models were contrasted by comparing the residual value sizes and distributions, and the model 4 was considered as the ideal with kinetic parameters as follows: apparent activation energy Eob was 1938394J/mol, apparent anterior factor k(0)ob was 3.0429×10-5mol/(m2·s·Pa). Through theoretical derivation based on these model parameters, the intrinsic kinetic equation of CO2 absorption by hot potash was obtained with following model parameters: the intrinsic reaction activation energy E was 5447kJ/mol, the anterior factor k0 was 3.2228×109m3/(mol〖DK〗·s). The conversion coefficient γ was calculated to be a value much greater than 2, which indicated that the CO2 absorption was a rapid reaction process that mainly happened in the membrane. 