The rod of the (Cu50Zr50)92Al8 (at%) bulk metallic glass(BMG) with a diameter of 2 mm was prepared by water-cooled copper mould sucking method, and its amorphous feature of the as-cast alloy was characterized by X-ray diffraction (XRD). The thermodynamic parameters of the bulk metallic glass were determined by differential scanning calorimeter (DSC). The alloy was compressed to different strains(20%, 60% and 80%) in the super-cooled liquid region, and the effects of the plastic strains on the microstructure and the thermal stability of the alloy were investigated. It is found that the deformation reduces the thermal stability of the alloy, and a partial crystallization occurs during the deformation in the alloy. The extent of the crystallization is strongly dependent on the deformation strain, and as the strain increases to 80%, the peaks of the crystallites can be clearly observed on the XRD pattern of the alloy. The present of the crystallites increase the mico-hardness of the alloy