Level of Repair Analysis (LORA) plays a significant role in Integrated Logistics Support Analysis of shipboard aircrafts,and is important for whole-system and whole-life management of the aircrafts.The current analysis model of LORA problem is insufficient for equipment mission and logistics support system.The analysis model is incomplete for LORA decision-making,and may affect the operational use and logistics support decision.To solve the problem,an analysis model of LORA is presented based on expected backorders (EBO) of spare parts.Firstly,the maintenance support mode of shipboard aircraft is analyzed.Then a multi-stage EBO model is established based on the actual situation of shipboard aircraft logistics support,and an optimization analysis model is presented based on EBO.Finally,analysis is made to the application of EBO based LORA according to an actual example.