Abstract: The transmitting and receiving performance of the antenna depends on the reflector precision and the structural stiffness of the antenna is the main performance index to determine the reflector precision, so it is very necessary to optimize the antenna structure. A vehicle-borne antenna with high stiffness weight ratio is proposed in this paper. Mechanical simulation analysis of the antenna self weight, wind load resistance and vibration load resistance is carried out by ANSYS finite element analysis software. The simulation results show that both well-shaped back frame structure and truss-shaped back frame structure can provide high stiffness structural support for the reflector; the truss-shaped back frame is superior to well-shaped back frame in strength and its maximum stress is 43.8 MPa smaller than that of the well-shaped back frame. The rationality and reliability of antenna structure optimum design is thus verified. The results can provide theoretical support for design of the same type of antenna.