This study was conducted to investigate the effects of dietary xylanase supplements at various levels on growth performance, nutrient digestibility, blood metabolites, fecal volatile fatty acids, and ammonia nitrogen in growing pigs fed wheat-based diets. One hundred and ninety-two growing pigs (Landrace×Yorkshire×Duroc) with an average body weight of 25.14±0.11 kg were randomly assigned to four treatments on the basis of their initial body weight. Each treatment had eight replicates with six pigs. The experimental period was divided into phases Ⅰ and Ⅱ(each 21 days). The dietary treatments were: 1) Basal diet (T1, control), 2) T2 (control+0.0125% xylanase), 3) T3 (control+0.025% xylanase), 4) T4 (control+0.0375% xylanase). Improved average daily gain, average feed intake, and feed conversion ratio were observed with increasing xylanase supplemental levels throughout overall experimental periods (p<0.05). In the nutrient digestibility, the pigs fed diets supplemented with xylanase showed a linear increase in dry matter, energy in phases Ⅰ and Ⅱ, and crude protein in phase Ⅱ with the progressive supplemental levels of dietary xylanase (p<0.05). Blood glucose concentration showed a significantly increased effect in linear impact with increasing xylanase supplementation in diets. Dietary xylanase treatments did not affect fecal volatile fatty acids and ammonia nitrogen concentration. The results of the present study demonstrate the potential of dietary supplementation of xylanase in improving growth performance, nutrient digestibility, and blood glucose concentration in growing pigs fed wheat-based diets. In addition, this study suggests that the proper supplemental level of xylanase is 0.0375% in growing pigs fed wheat-based diets.