Using Mg(OH)2, NH4H2PO4, ZrCl2O·8H2O as raw materials, MgZr4(PO4)6 (MZP) powder was synthesized by solid phase reaction method at four different heat treatment temperatures of 800 ℃, 900 ℃,1 000 ℃,1 100 ℃. The TG/DSC atlas, phase composition, micro-morphology, high temperature electrical properties of the synthesized MZP powder were investigated. The results show that pure phase MZP powder can be synthesized at 900 ℃, and the powder can exist stably. With the increase of the heat treatment temperature, the second phase product of Zr2O (PO4)2 appeared in the synthesis product, and its amount increased with the increase of the heat treatment temperature. The synthetic MZP powder has two forms, one is a granular shape with a size ranging from 2 μm to 5 μm, the surface is rough, and smaller particles are aggregated; the other is an irregular cube shape, and a very small amount of shape is rod-shaped with a smooth surface and a size of 2 μm. As the temperature increases, the conductivity of the MZP sample increases by three orders of magnitude due to the increased diffusion capacity of the magnesium ion channel.