The invention relates to a fermentation method for producing gentamicin by continuous feeding with an oxygen uptake rate (OUR) as a key control parameter. The fermentation method comprises a primary seed preparation, a secondary seed preparation and a fermentation production process. In the fermentation production process, a purpose of regulating and controlling the oxygen uptake rate is realizedby accurately controlling a carbohydrate supplement rate or a nitrogen supplement rate in fermentation process. In early stage of the fermentation process, when the OUR decreases from a peak value toa target OUR, feeding is started. During the feeding process, the OUR is maintained within a range of 15-30, so that metabolic activity of bacteria is maintained to make the bacteria have an ability to continuously synthesize gentamicin. Compared with the prior art, according to the method, regulation of OUR in the fermentation process is achieved through continuous feeding, the metabolic activityof bacteria is maintained, after entering a secondary metabolic antibiotic-producing stage in middle and later stages, nutrition is continuously supplemented, product synthesis is stable, titer is continuously increased, and continuous antibiotic-production is maintained very well. The method adopts automatic control and continuous feeding to maintain OUR, and is convenient for industrial scale control.