Chlorine atoms initiated oxidation reactions are significant for the removal of typical volatile organic compounds (VOCs) in the atmosphere. The intrinsic mechanisms of CH 2 =CHCOOH + Cl reaction have been carried out at the CCSD(T)/cc-pVTZ//M06-2X/6-311++G(d,p) level. There are hydrogen abstraction and C-addition pathways on potential energy surfaces. By analyses, the addition intermediates of IM1(ClCH 2 CHCOOH) and IM2(CH 2 CHClCOOH) are found to be dominant. The secondary reactions of IM1 and IM2 have been discussed in the presence of O 3 , O 2 , NO, and NO 2 . And we have also investigated the degradation mechanisms of ClCH 2 CHO 2 COOH with NO, NO 2 , and self-reaction. Moreover, the atmospheric kinetics has been calculated by the variable reaction coordinate transition–state theory (VRC-TST). As a result, the rate constants show negative temperature and positive pressure dependence. The atmospheric lifetime and global warming potentials of acrylic acid have been calculated. Overall, the current study elucidates a new mechanism for the atmospheric reaction of chlorine atoms with acrylic acid.