Abstract: In order to study the adsorption technology of CO₂ by soda lime in the underground emergency refuge space, and improve the adsorption capacity and the reaction rate of adsorbent, the influence factors of adsorptive property of soda lime were determined based on the soda lime chemical reaction mechanism and reaction rate. The effect of components, particle size and length on the adsorptive property was investigated through screening of common market soda lime, and the effect of adsorbent thickness and power of fan on the adsorption rate was investigated by orthogonal experiment, the optimum proportion of soda lime and the best working conditions was determined finally. The results show that the adsorption capacity increased first and then decreased with increasing of the ratio of water and NaOH, the optimum proportion and particle size of soda lime are that ratio of water and NaOH is 0.5, particle size is 6 mm, length is 30 mm; the best working conditions show that the adsorbent layer thickness is 8 cm, the fan power is 30 W.