Considering the structure function features and repair characteristics of HXD3 electric locomotive, the basic reliability evaluation model is established, and the reliability block diagram is provided by analyzing its system logic function relation roundly. Firstly, some factors that influence the reliability distribution of HXD3 electric, such as important degree, complexity, maintainability, testability, are analyzed. Secondly, the fuzzy comprehensive evaluation distribution method is proposed to evaluate the reliability of HXD3 electric locomotive system. Finally, taking locomotive failure rate as example, the reliability index allocation is analyzed and presented for locomotive system, sub-system, and components, especially the locomotive traction system.