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The corrosion resistance of Zr-0.7Sn-1.07Nb-0.32Fe-0.08Cr-xBi (x=0.1, 0.3, 0.5, mass fraction, %) alloys was investigated in superheated stream at 400 oC/10.3 MPa by autoclave tests. SEM and TEM equipped with EDS were employed to investigate the microstructures of the alloys and fracture surface morphology of the oxide film. Results show that when the Bi content is below 0.3%, there exists Zr(Nb, Fe, Cr)2 second phase particles (SPPs) with a hexagonal crystal structure (hcp). And when the Bi content is up to 0.5%, besides many Zr(Nb, Fe, Cr)2 SPPs, there are also a few Zr(Bi, Fe, Sn)2 SPPs with an orthogonal structure and Zr-Nb-Bi-Fe-Cr-Sn SPPs with an unidentified structure. This indicates that the maximum concentration of Bi in α-Zr matrix of T5+xBi alloys is 0.3%￡CBi<0.5%. The addition of Bi promotes the precipitation of Sn as SPPs, which is originally in solid solution in the α-Zr matrix of Zr-0.7Sn-1.07Nb-0.32Fe-0.08Cr alloy. When the Bi content is below 0.3%, the corrosion resistance of the alloys improves with the Bi content, but the addition of 0.5% Bi makes the corrosion resistance worse. It indicates that the solid solution of Bi in α-Zr matrix can improve the corrosion resistance, while the precipitation of the SPPs containing Bi and Sn is harmful to the corrosion resistance.