Fusion bead method produces homogeneous samples and is suitable for analysis using fundamental-parameter (FP) method in XRF. This report describes an FP method for analysis of non-oxide samples such as metals made into fusion beads. During the fusion process, all non-oxide elements in the sample are oxidized and gain-on-ignition (GOI) occurs. Volatile elements such as carbon do not remain in the sample as a result of fusion. This process is known as loss-on-ignition (LOI). To obtain reliable analysis results of fusion beads with the FP method, weight changes as a result of LOI and GOI must be reflected accurately in software calculation. The newly developed FP method, which takes these weight changes and dilution ratios into consideration, was able to yield accurate analysis results for ferroalloys FeSi, FeMn, and SiMn, some of which have high carbon content. This method is also applicable for sulfides and carbides.