Abstract: Magnesia-zirconia bricks with the microstructure of periclase covered by zirconia were prepared by improved technology after the technological parameters were determined by orthogonal test. In the microstructure of the magnesia-zirconia bricks, periclase crystals directly bond zirconia and zirconia is between two adjacent periclasc crystals; meanwhile, many micro closed porosities and fine zirconia crystals exist in the periclase crystals. Microcracks due to phase transformation of zirconia in the magnesia-zirconia bricks can absorb the fracture energy and result in the thermal shock performance of materials increasing; at the same time, micro closed porosities in the magnesia-zirconia bricks can reduce the heat stress and improve the mechanical properties of materials at high temperature. Fine zirconia crystals in the periclase crystals possess pinning effects which diminish and prevent creeping slippage in MgO-ZrO₂, and ulti-mately improve the hot modulus of rupture of the magnesia-zirconia bricks.