Sensitivity improvement of thermal ionization mass spectrometry (TIMS) is essential to ensure the analytical reliability, especially for the nuclear safeguard purpose. A feasibility study on the carburization of uranium samples to enhance TIMS sensitivity. Graphite powder in a suspension form was deposited onto rhenium filaments at a high temperature was performed. The uranium ion (238U+) intensity of TIMS was monitored to investigate the effect of chemical treatment of TIMS filament, as well as the evaporation behaviour and ionization of uranium under newly development conditions, and the dependence of such behaviour on graphite deposition concentrations. Determination of isotopic uranium ratios (n(234U)/n(238U), n(235U)/n(238U), and n(236U)/n(238U)) was performed using simultaneous measurement and continuous heating methods to confirm the validity of our technique, given that our analysis agreed with certified values.