Abstract: Based on the previous research results of the energetics and dynamics of vacancies and their clusters in tungsten, first-principles methods were used to systematically calculate binding energy and diffusion energy barriers of vacancies and their clusters. The results show that the electron exchange-correlation functionals PW91 and PBE are more suitable for calculating the energetic properties of vacancies in tungsten than PBEsol, AM05 and LDA functionals. Based on the first-principles calculation results, controversial issues such as the formation energy of the single vacancy and the nature of their interaction in the literature were discussed, and the empirical potential of tungsten was evaluated. The results show that the isolated single vacancies in tungsten always repel each other, while the vacancy clusters (V_n>3) have a strong attraction to single vacancy, and their binding energy increases with the number of vacancies in the cluster. The stable structure of vacancy clusters can be determined by minimizing their Wigner-Seitz surface area, and their binding energy is proportional to the difference in Wigner-Seitz area between V_n and V_n-1.