ZrN-based composites were synthesized from zirconia via aluminothermic reduction and nitridation proces with Al powders and Mg O as the reductant and sintering aids,respectively. ZrN-based composites are promising for application in the refractory materials or other high temperature industry fields. The effects of extra Al powder on physical properties,phase transformation and microstructures were investigated. Products with differen phase composition and morphologies were obtained with different Al powders additions. The products were composed of Zr N,ZrO_2,MgAl_2O_4,and Zr Al_3O_3 N by aluminothermal reduction and nitridation of zirconia with 0% extra Al powders addition. The diffraction peaks o Zr N were the strongest while peaks of ZrO_2 vanished with 6% extra Al addition. The thermodynamic calculation indicated that introducing Mg O into the system could promote the reaction process. ZrN-based composites were synthesized from zirconia via aluminothermic reduction and nitridation proces with Al powders and Mg O as the reductant and sintering aids, respectively. ZrN-based composites are promising for application in the refractory materials or other high temperature industry fields. The effects of extra Al powder on physical properties, phase transformation and microstructures were investigated. Products with differen phase composition and morphologies were obtained with different Al additions. The products were composed of Zr N, ZrO 2, MgAl_2O_4, and Zr Al_3O_3 N by aluminothermal reduction and nitridation of zirconia with 0% extra Al powders addition. The diffraction peaks o Zr N were the strongest while peaks of ZrO_2 vanished with 6% extra Al addition. The thermodynamic calculation indicated that introducing Mg O into the system could promote the reaction process.