Titanium carbide with low work function was formed on the surface of CNTs after deposition of a thin layer of titanium film and subseguest vacuum annealing at high temperature. The CNTs modified by titanium carbide was characterized by XPS, and the field emission characteristics of the CNTs film before and after modification were investigated. The characterization results indicated that carbon atoms reacted with the coated titanium atoms to form titanium carbide during annealing. The field emission measurements showed that, compared to that of unmodified sample, the turn on electric field of the modified CNTs film decreased from 1.21V/μm to 1.04V/μm and the emission current density at applied electric field of 2.34 V/μm increased from 2.3mA/cm2 to 13.5mA/cm2 Also, the emission stability of the titanium carbide-modified CNTs was improved. The mechanism of the CNTs film modified by titanium carbide has been discussed.