The dissolved oxygen control in the production of welan gum by Alcaligenes sp.NX-3 was investigated.Firstly,based on the analysis of the effect of various aeration rate on cell growth,welan gum concentration,glucose consumption,dissolved oxygen level,and welan gum viscosity,we confirmed that in a 7.5 L bioreactor 1 vvm aeration rate was beneficial for welan gum production.After that,the effect of different oxygen supply levels on the welan gum fermentation was studied.The results indicated that high oxygen supply level could improve the welan gum production,but it was not helpful for welan gum viscosity.Therefore,the two oxygen supply strategies:low-moderate-high oxygen supply level and high-moderate-low oxygen supply level were proposed.The results showed that the latter was better for the welan gum fermentation.Finally,the maximum concentration of welan gum reached 25.4 g/L with a yield of 0.51 g/g and the welan gum viscosity of 2.700 Pa·s.