Hexanitrostilbene (HNS) was synthesized via aerobic dehydrogenation of hexanitrobibenzyl (HNBB) with 4-hydroxyl-2, 2, 6, 6, -tetramethylpiperidine-1-oxyl (4-OH-TEMPO) combined ferrous chloride (FeCl₂) as catalyst in dimethysulfoxide (DMSO). The optimum conditions were obtained as follows: n(4-OH-TEMPO):n(FeCl₂)=4:6, solvent DMSO, reaction temperature 55 ℃, reaction time 8h, flow rate of oxygen 25 mL·h^-1 and the yield is 81%. The possible reaction mechanism is proposed as: HNBB oxidized by O₂ combined with Fe²⁺ to yield HNS, 4-OH-TEMPO as the co-catalyst to promote the circulation of Fe²⁺ and speed up the oxidation.