Abstract: An alkaliphilic strain namely YNUCCTCRQ1 of Bacillus sp.was isolated from hot spring of Tengchong,Yunnan.A 1 471 bp long fragment of 16S rDNA from the strain YNUCCTCRQ1 was sequenced and compared with closely related taxon in Gene Bank.The phylogenetic tree constructed by minimum evolution method indicated that YNUCCTCRQ1 was closely related to alkaliphilic B.halodurans C-125 and DSM 497T which produce xylanase. It was demonstrated that the YNUCCTCRQ1 xylanase was optimally active at pH value 7.5 and stable over a broad pH value range from 2 to 12.The optimum temperature for xylanase activity was 80℃ and the enzyme was relatively stable (below) 73℃.Co2+,Ni2+,Cu2+,Mn2+ and Hg2+ showed strong inhibition on the activity of the xylanase,while Ca2+,(K+,)Mg2+ and EDTA,bore a remarkable promotion on the enzyme activity.