A cellulose-degrading enzyme from Ganoderma lucidum was partially purified by ammonium sulfate precipitation and its enzymatic properties were studied. The enzyme had an optimum pH for activity at 4.0, and its stability range was pH $4.0{sim}7.0$. The optimum temperature was $55^{circ}C$ and the enzyme retained 80% original activity after heated at $50^{circ}C$ for 60 min. The activation energy of the enzyme for CMC degradation was caculated and found to be 6.2 Kcal/mole. The enzyme was activited by the addition of $Co^{++},;Mn^{++}$, but slightly inactivated by $Hg^{++}$. Various enzyme inhibitors and chemical reagents did not affect the enzyme activity. The enzyme acted on native celluose as well as CMC. The Michaelis constant for CMC was calculated to be 2.4 mg glucose ep/ml.