Abstract: For unique advantages of high altitude long endurance, near space long-endurance unmanned air vehicle using for radar detection possess wide development prospects in areas of space countermeasure and information confrontation. However, the limitation of load capacity leads to extremely harsh requirements on structure and weight of radar detection system. Platform-antenna integration is one of the key techniques to deal with this problem. Through the integrated design of antenna and air vehicle structure, antenna structure is the functional part of radar system, and also be the primary or secondary load-bearing part of air vehicle. In this paper, the antenna of radar system is integrated with platform structure; the platform-antenna integrated structure design is studied, and the integration of radar antenna structure function and the platform structure bearing function is achieved. The platform-antenna integrated structure is elaborated, and the simulational analysis of the stiffness and strength of integrated structure is carried out. The box-level structure verification testing by means of building block approach (BBA) is conducted. The results of structural strength test illustrate that the proposed platform-antenna integrated structure satisfies the requirements of stiffness, strength and stability.