It is well recognized that the development of highly efficient reduction is an effective way to remove Cr(VI) from wastewater. Herein, a novel carbon dioxide anion radical (CO₂^•-) production induced by UV-activated formic acid system is expected to offer a promising technology for removal of Cr(VI). In the present study, the activation and reduction mechanism have been investigated by comparing the reduction efficiency of the three reduction systems (UV、HCOOH、UV/HCOOH) and detection of electron paramagnetic resonance (EPR), which suggested that UV can significantly activate HCOOH producing CO₂^•-(α_H=19.08G,α_N=15.86G, g=2.0036). Moreover, the main influencing factors, including initial Cr(VI) concentration, dosage of formic acid, initial pH, reaction temperature, organic containments and common anions were also discussed, the results showed that percent Cr(VI) removal of 100% was obtained in 60min when the initial concentration of formic acid and Cr(VI) was 40mmol/L and 10mg/L, respectively. It was further revealed that percent Cr(VI) removal efficiency increased with the increase of formic acid concentration and reaction temperature, and appeared to be an acid-pH-favoured condition(pH£3.5). NO₃^- could remarkably promote the reduction of Cr(VI), while Cl^-, HCO₃^- and p-nitrophenol showed an inhibitory effects. From the fitting results of the removal kinetics data at different temperatures, it is clearly exhibited that the reduction of Cr(VI) by the UV/HCOOH system followed the pseudo-first order reaction kinetics after 40min. Arrhenius activation energy E_a were calculated as 15.9kJ/mol according to the rate constants k at different temperatures.