The structure, morphology, hardness, breaking toughness, strengthening and toughening mechanism of MoSi2-Si3N4(p)/SiC(w) composites were investigated by means of XRD, SEM, Vichers hardness tester and electrical omnipotence material tester in this paper. It is shown that the SiC whiskers and Si3N4 particles have the coordinated strengthening and toughening effect on MoSi2, the bending strength and room temperature fracture toughness of MoSi2-20 vol% Si3N4(p)-20 vol%SiC(w) composite are 427 MPa and 10.4 MPa·m1/2, respectively, which is higher than that of MoSi2 strengthened and toughened by SiC whiskers or Si3N4 particles. The strengthening mechanism of MoSi2-Si3N4(p)/SiC(w) composites are the fine grains and dispersion strengthening, and the toughening mechanism are the fine grain toughening and the crack deflection and the micro bridge join toughening.