Abstract: Liquid fermentation optimal condition of poria No.9 was studied in this paper by designing single factor experiments and optimization of orthogonal experiment. The results showed that the optimum fermentation medium includes glucose 30g, yeast extract and peptone 10g (the ratio was 4∶5) , KH2PO41g, MgSO40.5g, VB17.5mg in the water of 1L. The optimum cultivation conditions in the temperature of 25℃, rotation speed 150r/min were as follow:rinitial pH5.5, cultivation time 8d, liquid strain quantity of inoculation 7%, 70mL medium/250mL erlenraeyer, and the maximum mycelial dry weight could reach 5.004g/L.