Abstract: The rail defects of the high-speed railway are mainly oblique contact fatigue cracks, and these oblique cracks usually appear in series. The appearance of oblique cracks becomes an important factor which influences the safety of railway traffic. The inspection of rail oblique cracks is an important task in railway non-destruct testing field. Based on the magnetic flux leakage (MFL) testing techniques, this paper researches the recognition principles and methods of rail oblique cracks by the finite element analysis software Ansoft. The research contents include theoretical analysis, model establishment, the MFL signal differences between oblique crack and rectangle crack, and the recognition of depths and widths of oblique cracks, and the recognition of several parallel oblique cracks, etc. The conclusions could provide guidance for the further experimental research.