Xylanase B from thermophile bacteria Thermotoga maritima MSB8 has extreme-thermostability, which has potential widely application for feed, papermanufacture, energy, food and medicine industries. Recombinant pET28a(+)-xynB64 was induced and expressed in E. coli BL21(DE3), and the activity of recombinant XynB64 was very low. E. coli BL21-CodonPlus(DE3)-RIPL and Rosetta(DE3) both harbouring rare tRNAs were used to replace E. coli BL21(DE3) and the activity of recombinant XynB64 increased by 197% and 277%, respectively. However, some inclusion body was formed in E. coli Rosetta(DE3). Next, pET32a(+), pET42a(+), pET43.1a(+) and pMAL-c2X, which has the Trx, GST, Nus and MBP fusion tag respectively were used to replace pET28a(+) with E. coli Rosetta(DE3) as host. The activity of recombinant XynB64 produced by Rosetta(DE3)/pMAL-c2X-xynB64 was highest, which was equivalent to 88% of counterparts of Rosetta(DE3)/pET28a-xynB64. Meanwhile about 40 percent whole cell proteins of former were recombinant XynB64 with little inclusion body.