Abstract: The flexible antenna is conformal with the aerostat body, which can realize the lightweight design of the large radar antenna. That method is the technical basis for making full use of the aerostat platform to obtain the advantages of large line-of-sight detection. In this paper, an inflatable airbag antenna is designed. The layout of the antenna is designed according to the mission requirements and manufacturing capacities. On the basis of simulation and experiment, the material of each part and pressure of the entirety are confirmed. After several tests, the processing plan of the antenna is formed and the prototype is completed. To evaluate the compliance of the prototype indicators, two dimensions of structure and electrical performance are used to assess the prototype. In terms of structure, the appearance, size, reflector deformation, antenna verticality and time of shape retention all meet the requirements. In terms of electrical performance, the passive standing wave index is used to judge the performance of radiation element. By analyzing the data of transmission and reception azimuth pattern, it is determined that the prototype meets the indicators of antenna gain, sidelobe level, and beam width.