In this paper, magnesium aluminate spinel (MgAl2O4) materials were prepared by traditional solidphase sintering method with high purity fused magnesia and calcined active aluminum powder as raw materials, and NiO as additive. The MgO and Al2O3 powders were mixed in a theoretical molar ratio of 1∶1, and NiO with mass fraction of 0%, 0.5%, 1.0%, 1.5%, and 2.0% NiO were introduced into the system, respectively. The effects of NiO addition on sintering properties, phase composition and microstructure of MgAl2O4 were studied by Xray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that the introduction of appropriate amount of NiO can significantly promote the formation of MgAl2O4 phase and grain growth. At 1 600 ℃, when the NiO content is lower than 1.5%, NiO can completely dissolve into MgAl2O4 crystal lattice and preferentially replace Al3+, which improves the defect concentration in MgAl2O4 crystal and activates the lattice, thus promoting the sintering of MgAl2O4. When the NiO content is higher than 1.5%, more second phase NiO appears in the MgAl2O4, which hinders the mass migration and transmission, and it is not conducive to the improvement of sintering performance of MgAl2O4.