The evolution of microstructural and mechanical properties of ternary Zr-Cu-Al metallic glass under tensile loading was investigated by molecular dynamics simulations using embedded atomic potentials to describe interactions between atoms in the system. Special attention was paid to the variation of these properties according to the Al content in the Zr50Cu50-xAlx (0≤x≤50) system. The results showed that there is no systematic relationship between the elastic properties and the amount of Al, but the local structure of the system is significantly affected during the tensile load. The elastic modulus and yield stress were found to be maximum at 40 and 20 %, respectively. It was also revealed that the addition of Al decreased the fraction of Al-centered polyhedra, and increased the fraction of the same polyhedra around Cu and Zr.