MgO-CaO-ZrO2 composite materials were prepared in oxidizing atmosphere at 1550 oC with sintered magnesia, calcium oxide and partial stabilized zirconia as raw materials. Sintering performance of the composites was measured by the checking of the bending strength, the apparent porosity, the thermal expansivity and the thermal shock resistance of samples, respectively. The phase compositions and microstructures of the composites were investigated by XRD, SEM and EDS. The results showed that CaZrO3 phase was formed by high temperture reaction between ZrO2 and CaO, and phase compositions of the composites consisted of two phases of CaZrO3 and MgO. The sintering performance of composites were promoted further with increasing the content of ZrO2 due to the volume expansion caused by the reaction of the added ZrO2 and CaO to form CaZrO3 phase in the refractories.