Through a facile post-synthetic method, different kinds of polar group-functionalized ionic liquid porous organic polymers (POP-PA-COOH, POP-PA-OH, and POP-PA-NH₂) were obtained. The materials can be used as efficient heterogeneous catalysts in the cycloaddition reaction of CO₂ with epoxides under mild and co-catalyst-free conditions. It is demonstrated that POP-PA-NH₂ possesses much higher catalytic activity than POP-PA-OH and POP-PA-COOH. Interestingly, this activity difference can further be amplified when the reaction is carried out under low CO₂ concentration, and POP-PA-NH₂ possesses a conversion of 84.7% with a selectivity of 99.0% in 96 h. It is noteworthy to mention that research focusing on the transformation of CO₂ under low concentration using heterogeneous catalysts is rare and still a challenge. The excellent activities of POP-PA-NH₂ under low CO₂ concentration make this material a good candidate for CO₂ elimination under mild conditions.