Objective To analyze the propagation direction of rail surface crack. Methods The finite element method software ANSYS was used, and the stress intensity factors at the crack tip on rail surface were obtained for different locations of crack under conditions of different axle loads and crack angles. Results The stress intensity factor K was the maximum when the location of crack was at the edge of the contact area. The stress intensity factor K_I and K_II increased with the increase of axle load, while the stress intensity factor K_I increased and K_II decreased with the increase of crack angle. Conclusion The major rail surface crack was inclined crack at the initial stage of crack propagation and the propagation angle tended to be 60^o .