Influence of heat treatment on the microstructure and properties of TiC P/Fe composite by reactive synthesis at isothermal holding in liquid state was studied. The results showed that small amount of TiFe 2 and Fe 3C phases formed during solidification process are dissolved into matrix and a certain amount of secondary fine TiC reinforced phase is precipitated from the matrix during heat treatment. The matrix microstructure of the composite is completely changed during heat treatment. The composite with different matrix microstructure can be obtained through different heat treatment. The alloying element Mo is helpful to alter the matrix microstructure. Also the heat treatment has obvious effect on the properties of composite. The tensile strength increase and the impact toughness value decrease with the effect of secondary TiC on the matrix strengthening.