Based on the requirement of broadband radome, by using the transmission line theory, the calculation method of transmission efficiency of single-layer structure was conducted when the frequency varied from 2GHz to 18GHz and the incidence angle changed from 0 to 40°,the dielectric properties were optimally designed. The results suggest that when the dielectric constant is no more than 3.0 and the loss angle tangent value is no more than 0.02, the transmission efficiency of single-layer structure material with the suitable wall thickness is more than 60%. According to the design results, considering the mechanical and thermal properties, the hollow silica fiber reinforced BN-Si₃N₄ matrix composites (SiO_2f/BN-Si₃N₄ composites) are selected as single-layer structure radome material. According to the dielectric properties of the composites (ε=2.8，tanδ=0.005), the structural parameter (thickness) was optimally designed, and the optimal wall thickness was 7mm. The broadband properties of SiO_2f/BN-Si₃N₄ single-layer structure radome material in agreement with the wall thickness requirement were tested. The results suggest that the transmission efficiency for single-layer structure radome material is more than 60% when the frequency is 2～18 GHz.