The strain amplitude-controlled fatigue characteristics of an Al-Si casting alloy and its composite reinforced with 17vo1％ Al2O3 fibers (Al-Si/Al2O3) are studied at three different temperatures.Both the alloy and the composite showed different degrees of cyclic softening at elevated temperatures.Increasing the temperature,fatigue damage of either the alloy or the composite occurred with varying mode from brittle fracture of silicon particles to their separation from the aluminum matrix.This is explained by the different thermal expansion coefficients of silicon particles and the aluminum matrix.The reinforcement Al2O3 fibers in the composite showed a similar damage behavior with those silicon particles despite temperature variation.