Two ZrB2-based composites, ZrB2-20SiC and ZrB2-20SiC-10MoSi(2) (vol.%) were fabricated by hot pressing at 1900 degrees C for 1 h under 30 MPa. The effects of MoSi2 addition on the mechanical and anti-oxidation performances of ZrB2-20SiC composite were investigated. Compared with ZrB2-20SiC, the sinterability of ZrB2-20SiC10MoSi(2) was improved greatly, as the latter one achieved relatively fully dense bulk under the same sintering conditions. And the flexural strength and fracture toughness of ZrB2-20SiC-10MoSi(2) were increased remarkably. The main strengthening-toughening mechanisms of MoSi2 in ZrB2-20SiC-10MoSi(2) were considered as the pull out of elongated grains, bridging and deflection of cracks. Adding MoSi2 also improved the oxidation resistance of ZrB2-20SiC in air at 1800 degrees C due to the formation of a denser inner layer.