Mo-Ti-Zr-TiC/ZrC alloys were prepared via a powder metallurgy method. The effects of trace TiC/ZrC additive on the mechanical properties and microstructure of TiC/ZrC reinforced TZM alloy at room and high temperature were studied. The results indicate that the relative density and the tensile strength of Mo-Ti-Zr-TiC/ZrC alloy at room temperature are effectively enhanced by adding trace TiC/ZrC (0.1wt%~0.5wt%). The tensile strength achieves the highest value when the content of TiC/ZrC is 0.4wt%. Meanwhile, Mo-Ti-Zr-TiC/ZrC alloy with 0.4wt% TiC/ZrC shows excellent mechanical properties at 800 °C. The dispersive distribution of trace carbide particles accelerates the formation of dimples in the tensile procedure at elevated temperature, which leads to the transformation of fracture mechanism from the compound of trans-granular cleavage fracture and dimple fracture to simplex dimple fracture pattern.