Abstract: A method for the addition of nano-TiC to toughen martensitic steel belongs to the field of steel materials. In the addition of nano-TiC during remelting by a non-self-consuming vacuum electric arc furnace, active control of the size and content of the reinforcing particles is achieved, specifically: nanoparticles with a content of 0.1 to 0.5 wt.% are placed in the middle of the stainless steel sheet, the introduction of nanoparticles is achieved with the melting of the steel block, the movement of the melt pool is achieved by moving the tungsten rod at the cathode of the vacuum electric arc furnace, and repeated melting four times to ensure uniform dispersion of the nanoparticles . The diffusely distributed nano-TiC of the present invention becomes a heterogeneous nucleation center during the solidification process of the base martensitic steel remelting, which can serve the purpose of grain refinement, while the nanoparticles can also play the role of Orowan strengthening and thermal mismatch strengthening, achieving the simultaneous improvement of strength, hardness and elongation of martensitic steel. This method of martensitic refinement is universally applicable to martensitic steels, and the content and type of nanoparticles used are of general reference value for different steel grades.