The first principle based on the density functional theory and nonequilibrium Green's function method is adopted to study the energy level, the electronic structure and the electronic conductance of C32 molecular devices in which Au(1,1,1) electrodes are a ttached to the two farthest carbon atoms when different distances between electrodes and the central molecule are considered. The electronic transmission spectrum and I-V curves of the molecular devices at different distances are obtained. The reasons leading to the electronic structure and the electronic transmission characteristics are analysed. The impacts of the distance between Au electrodes and the central molecule and the gate-voltage on the electronic transmission are discussed. The results show that the distance between the central molecule and Au electrodes has greater influence on the electronic transmission characteristics. The results also show that the C32 molecule has obvious semiconductor characteristics.