Effect of Triton X 100 or water added on xanthan gum fermentation was with Xanthomonas campestris HL 9901 studied. It showed that: (1) 40ppm Triton X 100 added at the beginning of gum producing to the fermentation media had significant effect on the productivity, and its gum productivity reached 3.951g/100mL, exceeded the control by 11%. The carbon transformation ratio was 71.836%. However, it improved the viscosity of colloid by the addition of Triton X 100 at the initiate of fermentation is superior to the control. (2) If the carbon concentration was kept at 6.5%, the gum productivity reached 4.962g/100mL, increased by 15% when 20% water added after 36h fermentation, and the carbon transformation ratio was 76.338%.