Abstract: This paper provides the result about the design of a new type double shielded welding torch and the results of the experiments on gas shielding performance.It has been shown that the double shielded welding torch with "tri-water internal cooling" has a good shielding effect and prevents the positive double gas shielding effect from interference,due to the accumulation of spattering in a long welding time.The good action of gap effect of inner shielding gas flow provides the possibility by the use of gas baffle on the surface bead in the overlay and joint welding.