Zr-1.2Sn-1Nb-0.3Fe, Zr-0.4Sn-1Nb-0.3Fe and Zr-0.4Sn-0.65Nb-0.3Fe zirconium alloys with several different contents of Sn and Nb were treated by the same process, and the second phase particles(SPPs) in those alloys were investigated by SEM and TEM. The results show that the segregation of Sn exists in the SPPs to some extent, while Nb directly involves in the formation of SPPs. The SPPs are mainly composed of Zr(Nb,Fe)2with a HCP structure in all alloys.When Nb content is 1wt%, Sn content increases from 0.4w...