Abstract: Based on the outstanding advantages of the scaled boundary finite element method（SBFEM） for the problem of infinite domain,an improved numerical solution to the soil dynamic impedance of the nu-clear power plants is presented in this paper,by utilizing a continued-fraction solution of SBFEM analysis,which is especially fit for the numerical simulation of non-homogeneous layered soil region,and also can give the soil dynamic impedance varying with the excitation frequencies.Through the numerical example of a rectangular base,the rationality of the continued-fraction solution algorithm was shown.Finally,mainly aimed at the solution to half-space homogeneous/layered site problems,some numerical results are given to validate its accuracy and applicability by comparing with the harmonic response analysis of viscoelastic soil dynamic model.