The influence of heat treatment, specimen orientation and stress ratio on the fatigue crack propagation behavior of Al-Cu-Mg alloy containing Zr was studied. The results show that the difference of fatigue crack propagation rates between T3 and T4 temper specimens was not obvious. The effect of specimen orientation on the crack propagation rates was less significant. The fatigue crack propagation rates of the specimens in the L-T orientation and T-L orientation were similar. However, the stress ratio had a remarkable influence on the fatigue crack propagation rates; at the higher stress ratio, the fatigue crack propagation rates increased and the fatigue crack propagated rapidly into the high crack propagation regime to failure at lower ?K levels. The effect of stress ratio at near-threshold levels could be explained by a crack closure concept