In this work, the absorption and purification of H2S by palladium-copper liquid phase catalysis solution applied voltage was performed. The effects of electrochemical conditions, oxygen concentration, electrode material, voltage intensity and electrode plate spacing on the electrohydraulic synergetic purification were investigated by measuring H2S removal efficiency. The removal efficiency of H2S by electrochemical and liquid phase catalysis was better than that of pure liquid phase catalysis or pure electrochemistry. In the entire reaction system, oxygen played an important role in the production of active intermediate substances and the recovery of catalyst activity. The better electrode material was graphite electrode; the purification efficiency was slightly improved under large voltage conditions, along with the increase of energy consumption; the optimum electrode plate spacing was 5 cm. The mechanism of H2S gas purification with palladium and copper catalyst under external voltage was investigated in the selected conditions. In the reaction system, one portion of H2S was combined with metal ions to form metal sulfide precipitation. These metal sulfide precipitate was dissolved by electrochemical action and existed as ions in the solution to maintain their catalytic activity. The other portion of H2S was reduced to sulfur and SO42- under the catalytic oxidation of transitional metals and electroactive substances. Electroactive substances could restore certain catalytic activity of metal catalytic ions and form a catalytic cycle, which improved the purification efficiency of H2S.