The addition of TiO2 to alumina-magnesia refractory castables could accelerate the in situ spinel and calcium hexa-aluminate (CA6) formation and change the phase evolution, which will have direct effect on the overall modulus of rupture values. The cold (CMOR) and hot (HMOR) modulus of rupture, thermal expansion, and elastic modulus of alumina-magnesia refractory castables with different amounts of TiO2 were measured. The correlation of CMOR, theoretical strength, fracture toughness, and the fractal dimension of the fracture surface for these compositions were investigated. HMOR data were described using the model based on Varshni approach and Adam-Gibbs theory. The influence of TiO2 addition on the modulus of rupture of alumina-magnesia refractory castables was related to microcracks derived from expansive phase formation and pore filling or viscous bridging due to the presence of liquid phase at high temperature. The contribution of the above factors to the modulus of rupture for castables varied with the temperature.