MoSi₂ based materials are considered to have potential for use in high temperature structural part. In this work, MoSi₂/WSi₂ composites have been successfully prepared by pressureless sintering from mechanically-assisted combustion synthesized powders. The size of green powders shows great impact on the properties of sintered samples. The sample obtained from smaller powders has finer microstructure, and its Vickers hardness, flexural strength and fracture toughness were as high as 10.78 GPa, 327.21 MPa and 7.32 MPa m^1/2, respectively. The morphologies of the fractured surface of the composites revealed the mechanism to improve the mechanical properties of MoSi₂ matrix. Moreover, this composite exhibits good oxidation resistance at low temperature. A continuous SiO₂ layer was formed after exposure to air at 500°C for 120 hours, which could prevent further oxidation of the composite.