Zr48－xCu45Al7Gdx(x=0~7) bulk metallic glasses (BMGs) were prepared by injection in copper mould with arc melting. The effect of Gd content on the glass-forming ability (GFA), microstructures, fractured surfaces and mechanical properties of the alloys were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscope (SEM), hardness tests and compression tests. Results show that Gd content has evident effect on the GFA and mechanical properties, the rod-shaped BMGs with 4mm diameter can be obtained at Gd content of (2~5) at%. The BMGs possess a larger supercooled liquid region ΔTx with value of 73~79 K and a better reduced glass transition temperature Trg with value of 0.694~0.698, which consists of only amorphous phases with compression strength σb of 1768~1794 MPa and Vickers hardness of 5.08~5.32 GPa. In compression test of the BMGs a brittle fracture happens in pure elastic deformation way, and all fractured surfaces are flat and smooth with typical vein-like morphologies