Abstract: The oblique cracks are very dangerous in high speed railway, and rather difficult to be detected. In this paper electromagnetic techniques are used to solve this problem. By means of simulation and experimentation of rail sample, the relationship between the electromagnetic response of rail head material under excitation and the situation of defects and stress in the surface and subsurface is researched. The model also contains the variables of different feature of defects in the material and stress of the material. Based on the results of simulation, a Yoke and 3D magnetic sensor array is formed and PMFL, PEC effects are measured to get the feature of defects while the magnetic memory effect and Barkhausen noise are measured to get the information of stress formulation in a non-contact way.