This is an interatomic potential for the W-Ta alloy developed based on the Finnis-Sinclair formalism, in combination with the authors' previously developed potential for W. The potential parameters for Ta were determined by fitting to a set of experimental and first-principles data, including lattice constant, cohesive energy, elastic constants, point defects formation energies and Rose’s equation of state for the bcc lattice. The W-Ta cross parameters were fitted to the first-principles data of the formation energies and binding energies of Ta atom with different point defects in bulk W.