Abstract: Dry hyperbaric gas metal arc welding(GMAW) experiments with direct current electrode positive(DCEP) and direct current electrode negative(DCEN) were carried out. The process characteristics with different welding polar were studied at ambient pressure 0.1-2.0 MPa. By using DCEP, welding spatters appears when the pressure reached 0.2 MPa. Spatter generation level increases and spatter size decreases with increasing pressure. When ambient pressure is more than 0.4 MPa, welding process of DCEN is stable with nearly no spatter generation. The characteristics of two spatter types in DCEP were analyzed by high speed camera. The droplet deviated spatter is generated in the process of droplet repelled transfer. Another type of droplet rebounded spatter, is generated by the electromagnetic force. The reason of few spatters generating with DCEN was discwssed.