A method of preparing Cordyceps cicadae mycelium active substances for preventing and/or treating xerophthalmia is provided. The method comprises: (a) culturing a Cordyceps cicadae mycelium in a plate media at 15 to 35° C. for 5 to 14 days (b) inoculating the mycelium of step (a) to a flask containing liquid media and culturing it at 15 to 35° C. with a pH of 2 to 8 for 3 days (c) inoculating the mycelium of step (b) to a fermenter tank and culturing it at 15 to 35° C. with a pH of 2 to 8 for 3 days, so as to obtain a Cordyceps cicadae mycelium fermentation liquid (d) freeze-drying and grating the fermentation liquid, so as to obtain a Cordyceps cicadae mycelium powder (e) extracting the powder with solvent, so as to obtain a Cordyceps cicadae mycelium extract and (f) drying the extract, so as to obtained the Cordyceps cicadae mycelium active substances.
