The welded joint of duplex stainless steel is got by FCAW. The influence of flux-cored component,metallographic structure and solution treatment on the corrosive property of welded joint are researched. The pitting process and influence factors of weld metal FeCl3 are detailed analyzed. The pitting formation mechanism of the weld microstructure is studied,which is good for the application of duplex stainless steel in welding process. When increasing the proportion of austenite phase by improving the content of nickel alone,the corrosion rate of welded joints is large,adding element nitrogen is an effective way to ensure a reasonable two-phase ratio. The results show that the distribution,proportion, form and solid solution treatment of two-phase microstructure have great influence on the corrosion property,and the uniform microstructure is helpful to improve the corrosion resistance of the weld metal. By analyzing the pitting process of weld metal, it is found that the defects on the surface of the sample, such as porosity or slag inclusion,are generally the source of pitting,which will accelerate the corrosion rate,and the technological performance of the welding wire directly affects the corrosion property of the joint.