Understanding the melting behavior of tantalum under extreme pressures is critical for both fundamental science and high-energy-density applications. In this study, we investigate tantalum up to 450 GPa by integrating in situ X-ray diffraction measurements with ab initio molecular dynamics (AIMD) simulations. Experimental data confirm that the body-centered cubic (bcc) phase persists up to at least 318 GPa, as indicated by the continued presence of Ta(110), Ta(200), and Ta(211) diffraction peaks. These structural observations are consistent with recent high-pressure studies. The melting curve was computed using AIMD based on density functional theory, avoiding reliance on empirical potentials. The results align well with prior first-principles predictions and highlight the inadequacy of empirical models across wide pressure-temperature regimes. This combined experimental and computational methodology provides a reliable approach for investigating high-pressure phase stability and melting behavior in refractory metals, with broad implications for materials exposed to extreme conditions