The effects of La2O3 on the structure and properties of periclase-forsterite refractories were studied with fused magnesia and silica powder as main raw materials.The results showed that the introduction of La2O3 and their increase in content produce irregular,rod-shaped and needle-shaped lanthanum containing silicate phases between the main crystalline grains; The in-situ formation of the phases was conductive to improve the bulk density and decrease the apparent porosity of the materials,the mechanical properties and thermal shock resistance were also significantly enhanced；The enhanced microstructure from the in-situ formed lanthanum containing silicate phases elevated the penetration resistance of the materials to the melted glass batch and sodium sulfate.