Abstract: In this study, we expressed the gene of xynA in Pichia pastoris GS115 in order to realize the efficient expression and expand the application of xylanase in practical production. Meanwhile we treated yeast cells with inhibitor tunicamycin to analyze the effects on the expression and secretion of xylanase as well as the enzymatic properties. Results showed that the SDS-PAGE indicated that the xylanase was glycosylated, the molecular mass of glycosylated recombinant XynA was about 45 kDa and its activity was 406.6 U/mL. The recombinant XynA exhibited optimal activity at pH5.0 and 65℃. However, recombinant XynA treated with different concentration tunicamycin showed the same optimal pH but lower optimal temperature of 5℃. The activity, secretion and thermostability of recombinant XynA all decreased through the increased concentration of tunicamycin, when the concentration of tunicamycin was 15 μg/mL, 53.6% of the enzyme activity was left. But the deglycosylated recombinant XynA had a higher tolerance of pepsin compared with glycosylated recombinant XynA, Na⁺, K⁺, Li⁺, Ca²⁺, Al³⁺, EDTA revealed the activity treated with tunicamycin. The above results show that N-glycosylation plays a key role in the secretion and thermostability of xylanase expressed by Pichia pastoris GS115.