To predict the fatigue life of composite structures more accurately under random loads, some parameters are introduced, such as threshold value, elastic modulus, and fracture toughness. The overload hysteresis effect under random loads is considered to improve the crack growth rate model and obtain a random fatigue life prediction model. Taking the key components of the double-wishbone suspension as the research object, the random life prediction model for the key components was established, and the fatigue life test bench was built. By comparing and analyzing the numerical fatigue life, finite element simulation life, and physical test life, the effectiveness of numerical model and finite element model is illustrated.