A Cu55Zr40Al5 bulk metallic glass (BMG) was prepared by using copper-mold suction-casting and the structure and thermal stabilities of the amorphous alloy as well as the effect of isothermal annealing on its micro-hardness and friction property were studied. The results showed the glass transition temperature, onset temperature of exothermic reaction, and temperature interval of supercooled liquid region are 746.8 K, 793.5 K and 46.7 K, respectively. The BMG exhibits a micro-hardness value of 483.5 Hv and an average friction coefficient of 0.495. After isothermal annealing treatment, the micro-hardness has been enhanced and presents an upward trend with increasing the annealing temperatures. Meanwhile, the friction coefficients can be significantly decreased and the anti-wear property has been enhanced evidently.