Formation and mechanical properties of ZrCuAlSi metallic glass alloy was investigated by using differential scanning calorimetry (DSC), X-ray diffraction (XRD), microhardness test, and compression test. When the samples were prepared by using the simple copper mould casting, the maximum diameter of glassy rods increased from 4 mm for the Zr47Cu44Al9 alloy to 6 mm for the (Zr47Cu44Al9)98.5Si1.5 alloy without detectable crystal. Properly adding Si can enhance the GFA of the (Zr47Cu44Al9)100-xSix alloy and increase the microhardness(Hv) form 5850 MPa for the Zr47Cu44Al9 alloy to 6220 MPa for the (Zr47Cu44Al9)98.5Si1.5 alloy due to the suppression to form the primary CuZr phase. The compression test at room temperature shows that the (Zr47Cu44Al9)98.5Si1.5 alloy has the high fracture strength of 1862 MPa