An innovative additive, CaO-Al is utilized for the mechanochemical degradation (MCD) of chlorinated persistent organic pollutants (Cl-POPs). The introduction of Al into CaO significantly accelerates the reaction by promoting the release of electrons. The degradation efficiency of hexachlorobenzene (HCBz), 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (P.P'-DDD), and gamma-hexachlorocyclohexane (gamma-HCH) reaches 99.70, 97.75, and 99.71%, respectively, after 3, 1.5, and 8 h of milling. The stability of these organics in MCD follows the sequence of gamma-HCH > HCBz > P.P'-DDD, which is consistent with their degree of unsaturation.