Abstract: Tension-compression fatigue tests were conducted on ZL108 cast aluminum alloy and fatigue live at different stress amplitudes were obtained. On basis of three parameter exponential function, probabilistic stress amplitude-life (P-S-N) curves of ZL108 cast aluminum alloy were obtained. The limit state function for structure fatigue failure was established with fatigue life statisti data from fatigue tests to analyze the fatigue reliability, and was verified by experiments. The results show that the fatigue life of ZL108 cast aluminum alloy decreased with the increase of stress amplitudes, and had a great dispersion at each stress level. The logarithmic fatigue life of ZL108 cast aluminum alloy followed the normal distribution. The reliability calculated by established limit state function for structure fatigue failure were consistent with experimental results, and the maximum relative error was 5.71%.