Abstract: The sheet slanting tungsten electrode with rectangular section is employed to ensure application of great welding current for narrow gap welding process. The shape and current density distribution of arc current-carrying region can be analyzed by the low disturbance electrostatic probe. The results show that the sheet slanting tungsten electrode make the current density distribution more concentrate with 3~8° of hypotenuse tilt angle; because the current-carrying region section area of sheet slanting tungsten electrode arc is larger than that of cylinder tungsten electrode arc under the same welding parameters, the current density of sheet slanting tungsten electrode arc is smaller; the current density increased with larger welding current, and the heat concentrated near the center of current-carrying region section.