In order to avoid the design of the rotor of the dry gas seal high speed test stand occur resonance phenomenon during high speed running,the transfer matrix method was applicated to calculate the natural frequency.Then it obtains that its natural frequency is 14044.586r/min when the dry gas seal static and ring `s quality is 33.78 kg in rotor system,and using the finite element method analysis the modes of the rotor system when it is operating in the vicinity of its natural frequency,then it will get the modal figure with four modal value.Comparative and analysis the results of the two methods,though simplified model are not the same,the results are similar.And the design of speed can meet the requirements,so it can describe the design of the rotor system is reasonable.