The electronic transport properties of an (8, 0) SiC nanotube (SiCNT) with antisite defect are investigated with the method combined non-equilibrium Green’s function with density functional theory, in which the defect is formed with a carbon atom being substituted by a silicon atom. In transmission spectrum of the nanotube, a transmission valley about 1.68 eV near the Fermi energy is discovered, which indicates that the nanotube is a wide band-gap semiconductor. In its current-voltage characteristic, turn-on voltages of ±1.0 V are found under positive and negative bias. This originates from more orbital participating in its electronic transport properties caused by the bias. These results are meaningful to investigations on working mechanisms of SiCNT electronic devices.