Abstract: Factors influencing EDS analysis accuracy on carbon element in steel were analyzed, including choice of accelerating voltage, identification of sum-peak as well as the quantitative standardization. In addition, methods to improve EDS analysis accuracy on carbon element in steel were analyzed. The results show that the choice of accelerating voltage, identification of sum-peak and carbon contamination were factors influencing the accuracy of EDS analysis on carbon element in steel. The quantitative standardization was an effective method to increase the accuracy of EDS analysis on carbon element in steel. The more similar type of steel and content of chemical element between test sample and standard sample resulted in the higher accuracy analysis of EDS on carbon in steel.