Abstract: The \alpha decay half-lives of Pb isotopes in the range of 178≤A≤220 are investigated by employing a unified fission model(UFM) with consideration of the preformation factor, the generalized Royer (G−Royer) formula with the centrifugal potential and the Viola-Seaborg semi-empirical relationship (VSS). It can be seen from the comparison between experimental and theoretical half–lives that the centrifugal potential play an important role in the \alpha decay process. Furthermore, the good agreement between experimental and theoretical result indicated that the prediction of the unified fission model, the G−Royer and the VSS formulas are reliable. The half-lives of unknown Pb isotopes are predicted.