Abstract: 52 actinomycetes were isolated from the soil samples of different districts of China based on plate screening method, and 12 strains was obtained with enzyme activity over 100U/mL. Actinomycete F4712 with high xylanase-producing (the initial enzyme activity was 349. 4U/mL) was selected for further research. The conditions including:carbon source, nitrogen source, initial pH value, rotation rate, temperature and cultivation time were investigated by single-factor experiment. Box-Behnken was utilized to the response surface analysis to determine the conditions further, which were insoluble corncob xylan 2. 8%, a combination of beef peptone 1. 0% and yeast extract 0. 5%, pH 6. 2, 130r/min, 45℃ and 6 days. The xylanase activity was 693. 4U/mL under the optimal conditions, which was improved by 98. 5% compared to the original activity.