Some properties of cellulolytic enzymes produced by Pleurotus sajor-caju JAFM 1017 during its growth in synthetic medium were investigated. The optimum pH of avicelase, CMCase, and ${eta}-glucosidase$ was pH 5.5, pH 4.5 and pH 6.0, respectively. Avicelase and CMCase were stable within pH 5.0 to 6.0 and 4.0 to 6.0, respectively, and ,${eta}-glucosidase$ was within pH 5.5 to 6.5. The optimum temperature of avicelase, CMCase and ${eta}-glucosidase$ was the same of $40^{circ}C$. The enzymes were stable below the optimum temperature, but the enzymes were unstable over the temperature of $50^{circ}C$, and avicelase was losing about 91.7% of activity at $70^{circ}C$ for 10 min. The enzyme activity of avicelase and CMCase was increased in proportion to the substrate concentration within 1% and 0.7%, respectively, and ${eta}-glucosidase$ was within 0.1%. The Michaelis constants (Km) of avicelase and CMCase were 30.77mg avicel/ml and 14.64m Na-CMC/ml, respectively and ${eta}-glucosidase$ was 5. 13mg salicin/ml. The reducing sugar production of avicelase was proportionaly increased until 120 min. and CMCase and ${eta}-glucosidase$ were until 60min. The activity of three cellulolytic enzymes were increased by $Ca^{2+}$ at the concentration of $10^{-2}M$, but were inhibited by $Hg^{2+}$, $Ag^+$.