The identification equations for a rotor-bearing system equipped with a hydrodynamicbearing are formulated. The angles where the thrust bearing acts need not be measured. TheBFGS method combined with a hierarchical procedure is used to solve the identificationequations. The applicability of the frequency-domain method in the identi"cation of all theoil-film dynamic coefficients of journal bearings and thrust bearing is confirmed bynumerical simulation. It is also shown that the method is of high anti-noise ability.