Zr-Sn-Nb-Fe alloy is one of the high performance zirconium alloys used as the fuel cladding materials for high burnup fuel elements. The corrosion behavior of zirconium alloys were affected by the alloying element, the microstructure and fabricating process. To better understand the effect of Nb on the corrosion behavior of Zr-Sn-Nb-Fe alloy, Zr-xNb-0.4Sn-0.3Fe (x=0~1, mass fraction, %) sheets were prepared by thermo-mechanical processing and tested in static autoclave in 360 ℃, 18.6 MPa pure water, 360 ℃, 18.6 MPa, 0.01 mol/L LiOH aqueous solution, and 400 ℃, 10.3 MPa superheat steam. The characteristics of the microstructure were analyzed by TEM and SEM. It was shown that the corrosion weight gain of specimens was increased when x increaseed from 0 to 1 in pure water and steam. However, it was found that the corrosion weight gain reduced in LiOH aqueous solution as Nb content was increased. The microstructural characteristic indicated the addition of Nb has the effect of refining recrystallization grain of Zr-xNb-0.4Sn-0.3Fe alloy. The mean size of the precipitates in alloy were almost the same even though the Nb was considerably changed, but the area fraction of precipitates and mass ratio of Nb/Fe in precipitates of alloy were increased with the Nb content increasing when all the samples heat-treated in the same condition. The ZrFe or ZrNbFe precipitate of including small amounts of Nb was mainly formed when x was 0.2 or less, and the ZrNbFe precipitate was mainly found when the content of Nb was higher. With the increasing of corrosion rate, there are more cracks in the fracture surface of the oxide films and the size of “Cauliflower-like” structure grows bigger. It was concluded that the contents of Nb in ZrNbFe precipitates will be responsible for the difference of corrosion resistance for Zr-xNb-0.4Sn-0.3Fe alloy.