The TiZrHfNbTa system exhibits superior low-temperature plasticity compared to other refractory high-entropy alloys (RHEAs). Previous high-throughput studies utilizing magnetron co-sputtering and synchrotron X-ray techniques elucidated the phase transition from crystalline to glass/crystal nanocomposite, as well as their associated formation mechanisms. However, the thermal stability of such nanostructures has yet to be determined. In response, we propose a combinatorial approach based on high-throughput annealing methods to evaluate the phase and grain size stabilities of nanoscale TiZrHfNbTa with varied compositions. Results reveal that, as temperature increases, no obvious phase transition or grain growth occurs in crystalline BCC samples below 500 Celsius; however, amorphous samples undergo an obvious phase transition to BCC structure at only 200 Celsius. Nanoindentation mapping further demonstrates that an increase in grain size is associated with a change in hardness. Nanoscale TiZrHfNbTa appears to be inclined to form a more thermally stable state, similar to bulk-form samples with improved thermal stability under annealing. This indicates a potential avenue to bridge the gap between nanoscale and macroscale materials.