Abstract: Effects of pulsed parameters on weld penetration with the method of orthogonal experiment were researched when pulse power supply was applied to twin deposition electrode arc welding. Results of orthogonal experiment indicated the change of pulsed parameters could result in the corresponding change of weld penetration, and the descending order of pulsed parameters influencing weld penetration was as follows:peak current >frequency >duty ratio >base current. Greater penetration could be obtained with these pulsed parameters:peak current of 230-240 A, frequency of 3.3-3.7 Hz, duty ratio of 48%-52% and base current of 160-175 A. Optimal combination of pulse parameters of obtaining greater penetration is determined, which is frequency of 3.5 Hz, peak current of 230 A, base current of 160 A and duty ratio of 50%. Weld penetration increases when pulse power supply is applied to twin deposition electrode arc welding.