Abstract: In order to explore the reason of unqualified intergranular corrosion test of S32101 duplex stainless steel welded joint, metallographic examination, X-ray photoelectron spectroscopy (XPS) analysis and ferrite content test were carried out on welded joint which failed in intergranular corrosion test. The results show that the reason for the failure of intergranular corrosion test is that there is chemical composition segregation in the material, resulting in the low content of chromium, and chromium carbide precipitates at the grain boundary during the welding process, forming a chromium poor zone, which leads to the reduction of intergranular corrosion resistance of the material. In addition, the low content of ferrite in the microstructure also increases the possibility of the formation of chromium poor zone and further reduces the resistance to intergranular corrosion.