The crystalline structure refinement, chemical bond ionicity, lattice energy and coefficient of thermal expansion were carried out for Nd(Nb_1−xSb_x)O₄ ceramics with a monoclinic fergusonite structure to investigate the correlations between the crystalline structure, phase stability, bond ionicity, lattice energy, coefficient of thermal expansion, and microwave dielectric properties. The bond ionicity, lattice energy, and coefficient of thermal expansion of Nd(Nb_1−xSb_x)O₄ ceramics were calculated using a semiempirical method based on the complex bond theory. The phase structure stability varied with the lattice energy which was resulted by the substitution constant of Sb⁵⁺. With the increasing of the Sb⁵⁺ contents, the decrease of Nb/Sb–O bond ionicity was observed, which could be contributed to the electric polarization. The ε_r had a close relationship with the Nb/Sb–O bond ionicity. The increase of the Q × f and |τ_f| values could be attributed to the lattice energy and the coefficient of thermal expansion. The microwave dielectric properties of Nd(Nb_1−xSb_x)O₄ ceramics with the monoclinic fergusonite structure were strongly dependent on the chemical bond ionicity, lattice energy and coefficient of thermal expansion.