Abstract: The fatigue crack propagation behavior of A7N01P-T4 aluminum alloy with different loading angles was investigated. The crack tip stress intensity factor (SIF) under combined I-II loading mode was calculated using the finite element method. The relationship between the loading angle and crack direction was obtained, which agreed well with the maximum circumferential stress criteria. Then, the equivalent stress intensity factor (ESIF) was introduced to analyze the relationship between crack growth rate and loading angles. The results show that after quantization treatment, the crack growth rates under different loading angles are coincident, which also meet the Paris law.