The large low-speed wind tunnel is a new low-speed wind tunnel under construction in China. 3/4 open test platform is the one of the important test equipment in large low-speed wind tunnel. The collector and transition section structure are important parts connecting the 3/4 open test platform. During the test, the collector and transition section structure are subjected to dead weight and aerodynamic loads. The mechanical check is required during the component design. In this paper, the collector and transition section structure of 3/4 open test platform in large low-speed wind tunnel is studied. The strength, stiffness and dynamic mechanical properties of the components are analyzed by finite element method. The results show that the collector and transition section structure meet the design strength and stiffness requirements. The collector and transition section structure do not resonate in the dynamic analysis.