Abstract: To better understand the effect of tin on the corrosion behavior of Zr-Sn-Nb-Fe alloy, Zr-xSn-1Nb-0.3Fe （x=0-1.5） sheets were prepared and corroded by static autoclave in 360 ℃/18.6 MPa/0.01 mol/L LiOH aqueous solution for 340 days. The characteristics of the precipitates were analyzed by TEM. The results show that the corrosion weight decreases observably when the tin content reduces from 1.5% to 0.6%. However the corrosion weight increases when the tin content reduces from 0.6% to 0%. The microstructural characteristic by TEM indicates that the mean size and distribution of the precipitates in all tested alloys are almost the same even though the tin content is considerably changed, but the surface density in the alloy decreases with the increase of tin content when all of the samples heat-treated in the same condition. It is concluded that the solid solution content of tin in α-Zr is the main reason for the difference of corrosion resistance for Zr-Sn-Nb-Fe alloys.