Abstract: The fracture morphology, microstructure, chemical composition and tensile properties of a damaged rail head were tested by scanning electron microscope, optical microscope, direct reading spectrometer and tensile testing machine. The reason for formation of longitudinal-transverse kidney-shaped fatigue cracks was discussed and the solutions were proposed. The results show that under the cyclic working stress, the strip crack source was formed at the location of coarse inclusions distributed along the rolling direction in the wheel-rail contacted stress area of the rail head, and then fatigue propagation of the cracks occurred resulting in the formation longitudinal-transverse kidney-shaped fatigue cracks. Improving the purity of the rail steel, strengthening the control and inspection of metallurgical quality of the rail steel and reducing the quantity and refining the size of non-metallic inclusions were the main solutions to prevent the formation of longitudinal-transverse kidney-shaped fatigue cracks.