Abstract: The effects of different fed-batch methods on the biomass and ergosterol content in Saccharomyces cerevisiae were studied. The relationships of such parameters as pH, DO and concentration of glucose with biomass and ergoterol content were discussed under the circumstances of constant feed rate fed - batch, constant glucose - concentration fed - batch, exponential fed - batch, DO - control exponential fed - batch, pulse fed -batch, DO-control pulse fed-batch. Explanations and analysis of these phenomena were provided. According to the results of experiments, DO -control pulse fed- batch is an effective method for the fermentation of ergoterol. Compared with the traditional method, the actual yield (the product of biomass and ergoterol content) could be improved by 20% .