Abstract: Parathyroid Hormone(PTH)is one of durgs which could treat osteoporosis.Full-length human PTH(hPTH(1-84))nucleotide sequence was artificially synthesized,and after digestion with Nde Ⅰ and Sal Ⅰ,the fragment was inserted into pThioHis A.Then the recombinant plasmid was transformed into E.Coli BL21(DE3).At last,the hPTH(1-84)was recombinantly expressed by inducing of the IPTG.After studying on fermentation conditions,the best expression could be obtained when BL21(DE3)cultures were diluted 1/40 into medium with ampicillin including LB and 30% M9 salt,and grown at 37℃ to an OD 600 nm of 0.6,finally added 0.6 mmol/L IPTG and incubated another 8 hours.