Abstract: A 0.05 g sample was burned at 520℃ for 30 min, to remove the organic carbon in graphite. Then the carbonates were removed with nitric acid(1+1) and by the addition of 3 g of the carbon and sulfur analytical special mixed flux, the fixed carbon content was measured on the high frequency infrared carbon sulfur instrument. The method is simple, rapid, accurate, and reliable. The method is in good agreement with the indirect carbon fixation and non-aqueous titration volumetric methods. National standard reference materials (GBW03118, GBW03119 and GBW03120) and graphite ore samples were used to verify the method, the accuracy ranged from -0.11% to 0.04%, the precision was 0.52%~1.81%(RSD%, n=12), these indicators were in line with the DZ/T0130-2016 《geological laboratory testing quality management specification (analysis of rock and mineral samples chemical composition)》 requirements.