Abstract: In order to design and develop a high precision carbon fiber triaxial woven reflector of umbrella antenna, the carbon fiber triaxial woven reflector is selected as the research object. The material properties of carbon fiber fabric were obtained by experiment. The antenna reflector with different structure shape and different reinforcement scheme is designed. The finite element model of reflector under gravity filed is established for simulation. The relationship between the precision of the antenna surface and the shape of the reflector under the gravity filed is explored, and the optimal design scheme of the reflector is obtained. The optimization results show that the profile accuracy of polygonal aperture reflector is 9995% higher than that of circular aperture reflector. The profile accuracy can be further improved by 34% by designing the circumferential reinforcement on the polygonal aperture reflector. The research results provide reference and basis for the structure design of reflector.