Abstract: To optimize the brittleness of transition metal silicides at low and medium temperature, the Co₃Mo₂Si reinforced and Co-based solid solution (Co_ss) toughened Co_ss/Co₃Mo₂Si composites were in-situ synthetised by hot pressing sintering, using metal powders as raw materials, and the microstructure and mechanical properties of Co_ss/Co₃Mo₂Si composites were studied. The results show that the Co_ss/Co₃Mo₂Si composites mainly consist of Co₃Mo₂Si ternary metal silicide phase and Coss phase in uniform distribution. With the increase of Co₃Mo₂Si ternary metal silicide phase weight fraction, the hardness increases but the bending strength decreases; with the increase of Coss phase weight fraction, the relative density and bending strength increase. The maximum bending strength can be increased from 335.7 MPa of Co₃Mo₂Si single phase to 756.2 MPa of Co_ss/Co₃Mo₂Si dual phases.