A novel bulk metallic glass, Zr60.59Cu15.78Ni10.73Al10.75Nb2.15, was obtained by micro-alloying of brittle ZrCuNiAl bulk alloys with Nb addition. The structure and thermodynamics parameters were determined by XRD, DSC and HRTEM, and the mechanical properties were studied by quasistatic compression. Although XRD and DSC results show the glass nature of the alloy rods, HRTEM surely indicates the precipitation of nanocrystals of 1-2 nm in the as-cast alloys. The Nb addition significantly reduces the crystallization activation energy of Zr-based alloy and favors the further nucleation of nanocrystals during the subsequent deformation. The nanocrystals increase the potential nucleation sites of shear bands, inhibit the propagation of shear bands, and disrupt the operating shear bands; therefore the room-temperature plasticity of the alloy is largely improved. The yield strength, the average plastic strain, and the maximum and minimum plastic strain for the Zr60.59Cu15.78Ni10.73Al10.75Nb2.15 alloy are 1850 MPa, 11.95%, 25.37% and 2.95%, respectively. There is also strain-hardening phenomenon