Plankett Burman design is applied to choose the optimum cultivation conditions which may influence the cultivation medium of Cordyceps militaris mycelium liquid and cultivation environments.Taking the yield of Cordyceps militaris mycelium with different medium as index,we optimize the cordyceps fermentation conditions.Both the response method and central combination design are used to optimize the technical parameters which are following: Glucose 23.34 g/L,corn plasma 12.5 mL/L,inoculation quantity 9%,fermentation temperature 25 ℃,KH2PO4 1 g/L,MgSO4·7H2O 1 g/L,VB1 2 g/L,fermentation speed 150 r/min,pH 7.0.At the optimal conditions the product of the mycelia biomass is 15.59 g/L matched to the estimated value 15.56 g/L,which show that the estimated model can be used to predict the yield of the Cordyceps militaris mycelium liquid.