Abstract: Key hole TIG welding of 10 mm thick TA2 plate was conducted. The microstructures, hardness, tensile strength, bending properties and impact properties of the welded joints were investigated. The impact fracture of the specimens with notch machined at the center of weld was observed by scanning electron microscope. It has been verified that one side welding both sides formation of 10 mm thick TA2 plate without notch can be successfully obtained by using the optimized TIG welding parameters; high welding current accounts for coarse grains of the weld, but impact value in the weld center doesn't reduce obviously and that around the fusion line is slightly higher than that of the base material; the joint has good bending performance; the strength and hardness are equal to those of the base material.