The effects of Zr addition on the microstructure and magnetic properties of the sintered NdFeB magnets were investigated by X-ray diffraction (XRD) and BH magnetic tester. The XRD analysis showed that both the Zr-free and Zr-doped samples are composed of main amount of Tetragonal phase Nd2Fe14B (P42/mnm) and trace amount of Nd-rich phase, but adding Zr reduces significantly the values of pole density factor of (004), (006) and (008) crystal faces for the sintered Nd(Fe,Zr)B magnets estimated by Horta-formula. Accordingly, the coercivity of the sample with Zr addition is reduced from 2038 kA/m down to 1951 kA/m. The study of the Kronmüller-plot shows that the nucleation is the dominating mechanism for the magnetization reversal in these two kinds of magnets, and two microstructural parameters of αk and Neff are obtained also.