[en] The influence of nonstoichiometry of Na on micronmicrowave dielectric properties of Na_{0.5+ x} Nd_0.5TiO₃ (N x NT) ceramics was systematically investigated in this research. The main phase of samples was indexed as cubic perovskite structure, and Nd_0.667TiO₃ was detected as secondary phase (−0.05 ≤ x ≤0), which was caused by the evaporation of Na ions. As x was increased from 0 to 0.05, the Nd_0.667TiO₃ phase was effectively eliminated and the densification process was improved. Therefore, the ε_r and Q×f initially increased, later they decreased, which was accordance to the change of density. The τ_f value didn't show a dramatic change, and a relatively low value of 248.2 ppm/°C was obtained at x =0.05. Excellent microwave dielectric properties of ε_r =110, Q×f =8115 GHz and τ_f =248.2 ppm/°C) were (paper)