Abstract: TIG welding test of 12 mm thick TA18 titanium alloy plate was carried out by using 2B solid core welding wire.The microstructure, the electrochemical and stress corrosion behavior in different corrosive media of the TA18 titanium alloy TIG welding joint were studied.The results show that a large number of coarse columnar crystals and a small amount of equiaxed crystals are distributed in the TA18 titanium alloy joint′s weld area, part of net basket organization exsits in the cover, bottom and intermediate filler layers.The microstructure of the heat-affected zone is mainly composed of needle-like α'(α'') phase, residual α phase and β phase. When the electrochemical corrosion test is carried out in 3.5% NaCl solution, the corrosion resistance of each region of the TA18 titanium alloy joint from high to low is as follows: base metal, weld, heat-affected zone. Comparing the slow strian rate tensile stress-strain curves of the TA18 titanium alloy joint in air and simulated sea water, the mechanical properties of the joint are not significantly affected by seawater and it has low stress corrosion sensitivity to seawater.