The cDNA encoding human manganese superoxide dismutase was amplified from the human liver total RNA by RT-PCR, ligated into pBV220. The cloned gene was analyzed by restriction enzymes EcoR l, Sal Ⅰ, and BamHⅠ. The sequence of the cloned gene was determined. hMnSOD was induced and expressed upon temperature shift from 32℃ to 42℃.Mn²⁺ supplementation in the bacterial growth media resulted in about 3-fold increasing of SOD activity. The special protein expressed accounts for 14% of the total protein of the bacteria.