Based on the fatigue failure theory of gear,the gear CAE model was established by using Workbench and nCode methods to complete the gear contact dynamics and fatigue life prediction analysis.The static and transient characteristics of gear pairs were analyzed with main influencing factors of fatigue durability as the characterization parameters.Based on the material S-N curve and Miner linear damage theory,the fatigue reliability of gear pairs were analyzed through nCode Design-Life software under given different load spectra,and the fatigue result cloud diagrams of gears’ contact region and fatigue life of each node were obtained.The results show that the maximum contact stress are in the same areas as the minimum fatigue life of the gear transmission under static load conditions;the minimum fatigue life appears in the transition regions between the tooth surface reference circle and gearend surface under dynamic load conditions;no matter under the static or dynamic load conditions,there are all great influence for torque change of driven gears on the fatigue life of gear transmissions.The study results can provide reference for the design of anti-fatigue optimization and acceleration test.