Using first-principles density functional theory and non-equilibrium Green’s function method, we investigate the electronic transport properties of Na@C20H20 molecule. The calculational results show that the I-V curve exhibits good linear characteristic in the range of bias V, and shows obvious negative differential resistance (NDR) characteristics. The equilibrium conductance of Na@C20H20 molecule is 0.0101 G0. Comparing the results with those of Li@C20H20 molecule, we find that doping Na can improve both the electronic transport capacity and the chemistry stability of C20H20 molecule, which makes it more suitable as candidate of molecular device.