Using the technique of colored metallography, the phase compositions of two medium-/low-carbon low-alloy carbide-free bainite steel used for railway crossings are obtained. The etching of the samples was carried out using the Lepera reagent and a mixed reagent of hyposulphite and picric acid respectively. The proportion of the bainite phase was calculated using an image processing system with an optical microscope and the residual austenite content was measured using XRD method. The martensite phase content can then be determined. It is found that the reagents can effectively and quantifiably analyze the phase composition of bainite steel and produce approximately the same results.