The strain of HL- 9901 induced from Xanthomonas campestris was used in the experiment. with orthogonal design and statistical analysis, the optimal prescription for fermentation was composed of 4 % starch, 2 % glucose, 0. 1 %peptone, 0. 1 % NaNO3, 0. 3% (NH4 )2HPO4, 0. 3% K2HPO4, 0. 1 % MgSO4, and 0. 09% CaCO3, and 1. 5 % glucose was supplemented after 30 hours fermentation. The final productivity of xanthan gum was 4. 063 g/100mL, the transformation of carbon source was 54. 17% and the time of fermentation could t,e shortened to 54 hours. Meantime, some relevant parameters were measured in the course of fermentation with the optimized culture.