This work investigates the high temperature decomposition process of theε-phase obtained by means of splat quenching in the Fe-C-Sb alloy by using differential thermal analysis, quenching sample X-ray diffraction analysis and powder photography employing Guinier-Lenne transmission high temperature monochromatic focusing camera. The results indicate that the ε-phase begins to decompose at 125℃. At first, it decomposes into ε-Fe2C, then α-Fe, Sb and Fe3Sb2 appear at 450℃, but ε-Fe2 Cremains at that temperature. Above 550℃, the ε-Fe2C phase transforms into Fe3C. The transformation of the α-Fe→γ-Fe was found to be at 770℃, and at 800℃ the main phases are:γ-Fe, Sb and Fe3C. The transformation of the γ-Fe→α-Fe was found to take place at 750℃during the cooling. The main phases at room temperature are:α -Fe, Fe3C, Sb and Fe3Sb2.