Abstract: In order to obtain xylanase with good acid and alkali resistance, to solve the application problem of xylanase in the actual industry. In this study, xylan was used as the sole carbon source. From the intestines and feces of Yibin bamboo rats, the Congo red fading method was used to determine the xylanase activity for re-screening, and one strain with alkaline xylan was screened. Carbohydrase activity strain JZF, 16S rDNA sequence analysis, identified as Bacillus mycoides, the growth curve of Bacillus mycoides JZF, the enzyme production curve and the enzymatic properties of alkaline xylanase explore. The results showed that the enzyme activity of this strain reached 15.17 U/mL after cultured at 37 ℃ and 180 r/min for 48 h; the amount of bacteria reached the maximum after 28 h, the xylanase activity reached the maximum after 72 h, and the most suitable reaction temperature for the produced xylanase was 50 ℃, and the optimum pH was 9.0; the relative enzyme activity could be maintained above 60% under the conditions of 40~60 ℃ and pH8.0~9.0. The metal ions Mn²⁺ and Ca²⁺ had obvious effects on the xylanase of this strain. The xylanase produced by the strain obtained in this study has good activity under alkaline conditions, which provides a source and data basis for the subsequent practical application of alkaline xylanase.