Abstract: The antenna is equipment to receive and transmit electromagnetic waves. Its performance affects greatly the accomplishment of spaceflight assignment. According to the assignment of spaceflight and space environment such as the complicated mechanics condition at the launch stage, thermal vacuum condition in orbit etc. , a new space-borne screw antenna is designed. Its mechanics analysis is carried out from static strength,dynamic strength and stiffness of structure and the fundamental frequency and safety margin are calculated. The result shows that the antenna structure fully satisfies the requirements of mechanics environment. The sample has passed the random vibration test and thermal vacuum environment test. The antenna structure is simple, reliable,convenient to manufacture and has good adaptability for space environment,especially the extreme thermal environment. It can be used as guidance for the structure design of similar space-borne screw antenna.