This paper aims at the contradiction between the surge of airborne energy demand brought by the requirements of new quality combat capability such as omni-directional detection and omni-directional attack of high-performance UAV and the requirements of platform performance such as long range and long endurance and the cost of airborne energy system, combing the main factors affecting the weight of the airborne energy system, carrying out the analysis of the design concepts of UAV energy system lightweight, combining with the statistical data of the field operation of the aircraft airborne energy system in service, analyzing the current status of the design technology of airborne energy system, exploring the lightweight approaches of airborne energy system from the perspectives of energy demand, system architecture, control strategy and basic finished products, and proposing the design methods and suggestions of UAV energy system lightweight.