Abstract: 2205 duplex stainless steel was selected as the research material. The microstructures of different regions of the welded joint were characterized using optical microscopy (OM) and scanning electron microscopy (SEM), and the phase fractions were calculated. The pitting corrosion resistance of various weld regions was evaluated through potentiodynamic polarization tests and critical pitting temperature (CPT) measurements. Furthermore, the micro-morphology after electrochemical testing was observed to investigate factors influencing pitting corrosion. The results show that filler the heat-affected zone (HAZ) exhibits the lowest austenite content and the presence of Cr₂N precipitates, while the weld layer has the highest austenite fraction. The root pass region shows a relatively low austenite content, with fine and dispersed intragranular austenite (IGA) and a considerable amount of secondary austenite. In the HAZ, the combination of Cr₂N precipitation and minimal austenite content results in the poorest pitting corrosion resistance. The root pass, affected by subsequent thermal cycles, also forms secondary austenite, leading to lower corrosion resistance compared to the filler and cap layers. The base metal demonstrates the best pitting resistance overall, though Mg-Al-O oxide inclusions within it can serve as initiation sites for pitting corrosion.