By using crystal-field theory, the optical spectra and spin-Hamiltonian parameters (abbr. SH parameters, i.e. the anisotropic 𝑔 factors $g_{\|} g_{\perp}$, and hyperfine structure constants $A_{\|}, A_{\perp}$) of 171Yb3+ and 173Yb3+ isotopes in the tetragonal PbWO4 are calculated. The theoretical results agree well with the experimental values. The crystal-field parameters and the signs of the hyperfine structure constants for both 171Yb3+ and 173Yb3+ isotopes are determined. The validities of the theoretical results are discussed.
