Abstract: Welding experiments were conducted on 3 mm and 6 mm-thick TC4 plates by PC PAW and"one keyhole per pulse"PAW for the purposes of testing the appearances,the internal welding deflects and mechanical performance of the welded samples. And the processing properties of the two techniques were also compared. The results showed that the mechanical properties of the welded samples could meet the standards related; the welded joint appearances of "one keyhole per pulse"PAW were smooth and uniform,and the fronts of the welded joints didn't subside. The mechanical properties and the SEM test showed that"one keyhole per pulse"PAW is more suitable for TC4 PAW.