To improve the resistance to hydration, thermal shock and slag penetration of magnesia, a magnesia based composite was prepared via adding TiO2 powder (i.e., 1% (in mass fraction), 2% and 3%) into a light burned magnesia powder. The effect of TiO2 content on the sintering behavior, microstructure and properties of the composite was investigated. The results show that free CaO and some MgO transform into CaTiO3 and Mg2TiO4 and the size of MgO grains increases as TiO2 addition increases, leading to an improvement in the hydration resistance. The formed CaTiO3 and Mg2TiO4 phases reduce the thermal expansion coefficient and induce the crack deflection as TiO2 content increases, therefore improving the thermal shock resistance of the specimens. Besides, as 1% TiO2 is added, the slag penetration resistance of the specimens is enhanced due to the increase in MgO grain size and the formation of high stable intergranular CaTiO3 phase. However, the further increasing TiO2 content reduces the slag penetration resistance due to the formation of low stable Mg2TiO4 phase at MgO grain boundaries.