Niobium acts as a main alloying element in the third generation zirconium alloys. The role of Nb element in the alloys is greatly concerned. The influences of Nb content on the microstructure and recrystallization process of Zr-xNb (x=0, 0.3, 0.7, 1.0) alloys were studied by means of transmission electron microscopy (TEM), optical microscopy (OM) and Vickers micro-hardness testing. The results show that with increasing Nb content the quantity of the precipitates increases and the mean size of the precipitate particles decreases. Meanwhile, the recrystallization process is slowed down by the precipitates, especially in the case of Zr-1Nb alloy. The main precipitates were found to be Zr(Nb,Fe,Cr)2 and β-Nb in Zr-0.3Nb and Zr-1Nb, respectively.