Abstract: In order to investigate the effects of the oxidation and reduction pre-treatment on the combined oxidation-reduction techniques in the remediation of nitrobenzene contaminated groundwater, 2, 4-dinitrotoluene (2, 4-DNT) was chosen as the target contaminant and the persulfate-iron-carbon remediation technology system was constructed. Specifically, a large experimental trough of persulfate as oxidation pre-treatment combined with subsequent reduction post-treatment of iron-carbon mixture material and iron-carbon mixture material as reduction pre-treatment combined with subsequent oxidation post-treatment treatment of persulfate were set up. The effects of oxidation and reduction pre-treatment on 2, 4-DNT removal mechanism in the combined oxidation-reduction system were compared and studied. The results showed the filling position of persulfate material significantly affected the changes of pH and oxidation-reduction potential (ORP) in the large experimental trough. The pH could be significantly increased to about 11, and the ORP value reached the highest in the 5 pore volume (PV). Within 5 PV, the concentration of persulfate in the oxidized packed layer and the concentration of Fe²⁺ in the reduced packed layer decreased significantly. Within 5 PV, the removal efficiency of 2, 4-DNT in the large experimental trough of persulfate as oxidation pre-treatment combined with subsequent reduction post-treatment of iron-carbon mixture material was significantly reduced, whereas that in the large experimental trough of iron-carbon mixture material as reduction pre-treatment combined with subsequent oxidation post-treatment treatment of persulfate was maintained at 100%. The main intermediates of 2, 4-DNT degradation in the combined oxidation-reduction techniques system were identified by liquid chromatograph mass spectrometer (LC-MS). In combination with the iron-carbon micro-electrolysis reduction mechanism and persulfate oxidation mechanism, the collaborative treatment mechanism and possible degradation paths were proposed. Our results showed that the experimental trough of iron-carbon mixture material as reduction pre-treatment combined with subsequent oxidation post-treatment treatment of persulfate was more beneficial to the 2, 4-DNT removal in the combined oxidation-reduction remediation system, which provided theoretical support for the effective treatment of nitrobenzene contaminated groundwater.