In this thesis, mechanical and electronic properties of a (4,4) SiC nanotube under different tensile strain were investigated by density functional theory (DFT) calculation. The HOMO-LUMO gap of nanotube will significantly decrease linearly with the increase of axial strain. Two different slopes are found before and after an 11% strain in the profile of HOMO-LUMO gap versus strain. The partial density of states, bond order and electronic deformation density were discussed for demonstrating the strain effect on the electronic properties of SiC nanotube under axial strain. The adsorption mechanism of CO on SiC nanotubes with different axial strains as well as the charge distributions after the adsorption were also discussed.