Abstract: Aiming at the current extensive use of large frame structure projects with discrete topology optimization and the disregarding of manufacture techniques, this paper proposes an accurate mathematical description of intersection, puts forward the concept of intersection-factor, and establishes a continuous function from the cross-sectional area design variables to intersection-factor by using the Heaviside function. Then we add intersection-filter constraints in the optimization model, and the Ground Structure Method is used to set up the topology optimization model. Finally the method is applied to the design of an antenna radial girder, the result shows that the proposed method can effectively eliminate the undesirable member's interferences.