Immobilization of Gluconobacter oxydans cells and conversion of ethylene glycol to glycolic acid in bubbling reactor were investigated. The optimum of immobilization was 8%PVA, 0.8% sodium alginate and 0.27g cells biomass per milliliter gel. The immobilized cells were more stable than free cells in pH and thermal stability. Conversion of ethylene glycol to glycolic acid was carried out in bubbling reactor. When the initial ethylene glycol was 70g/L, the first cycle conversion was 92.6%, and it could successively convert six cycles, the average conversion was about 85%.