A method for treating renal disease is provided in the present invention, and the method includes the step(s) of: administering a Cordyceps militaris extract to a subject in need thereof. Preferably, the Cordyceps militaris extract is manufactured by a method including the step(s) of: grinding a fruiting body of Cordyceps militaris into powders； mixing the Cordyceps militaris powders with ethanol to obtain a mixture； filtering the mixture to obtain a filtrate； and drying the filtrate to obtain the Cordyceps militaris extract.
