The ZrCuTi thin film metallic glasses (TFMGs) with immiscible Ta were successfully fabricated via co-sputtering. The glass forming composition for ZrCuTi-Ta TFMGs ranges from 0 to ~. 75 at.% of immiscible Ta, distinctly different from bulk metallic glasses (BMGs). When Ta content is over 75 at.%, the amorphous TFMG structure gradually transforms to nanocrystalline β-Ta. The mechanical properties are strongly influenced by Ta content. The elastic modulus remains nearly constant over 0-50 at.% Ta, and increase rapidly over 50-100% Ta. The key factor appears to be the population of the Ta-Ta strong bonds. The highest elastic modulus and hardness up to ~. 140. GPa and 10. GPa, respectively, of the Ta-rich TFMGs, much higher than the Zr-, Cu- and Ti-based amorphous alloys, might be useful for applications.