A calculation method was proposed to calculate contact stiffness between interfaces in a view of modal experiment on the basis of Hertz contact and Greenwood-Williamson (G-W) model. Formula with coefficient for calculating contact stiffness was deduced; afterwards the first order natural frequency curves with various contact stiffness coefficients were drawn by using numerical simulation. The contact stiffness coefficient was chosen via experiment data of the first order natural frequency

and then the formula for calculating contact stiffness was obtained. The first order natural frequencies under different centrifugal forces and different geometry models together with vibration response under exciting force were calculated using corrected formula

and comparisons were made with experiment data. The maximum calculation error of the first order natural frequency is 1.73% and that of vibration response is 9.5%

which agree well with experiment data and testify the validity of method. Analysis of damping effect caused by dry friction on system vibration attenuation was also conducted and evident vibration attenuation is found near the first order natural frequency.