We　report　a　theoretical　study　on　the　electronic　structures　of　O2　chemisorbed　on　a　(8,0)　SWNT　with　different　oxygen　contents　of　6.25,　12.5　and　25%,　respectively.　On　the　basis　of　DFT　calculations,　we　find　that　eight　O　2　molecules　chemisorbed　on　the　(8,0)　SWNT　aligned　in　the　middle　row　of　the　circumference　of　the　tube　in　proportional　spacing　way,　is　seen　to　become　metallic,　and　a　significant　increase　in　conductivity　is　expected.　There　are　different　electronic　structures　of　the　functionalized　systems　related　to　different　oxygen　contents　or　O2　molecules＇　chemisorbed　positions.