This paper adopts a dual-point measurement technique to predict the resonance frequency and operation modes of a high speed rotor at different operating speed. The effect of balance policy on the operating mode shapes of a rotor has also been investigated. Displacement signals measured at two different points of a rotating shaft are used to estimate the operation mode shapes at the main operating frequency based on the definition of transmissibility function. To verify the feasibility of this technique, the dynamic parameters, i.e. natural frequencies, damping ratio and normal modes of a stationary rotor are measured in advance by applying the traditional frequency response method for comparison. The values of modal assurance criterion (MAC) and mode shape diagrams indicate that both methods are in a good agreement on the normal modes when the system is undamped or lightly damped. However, a significant difference is observed for highly damped modes. The dual-point measurement technique is applicable to investigate the effect of rotating speed on measured operation modes at different speed. Results indicate that the rotating speed may affect the dynamic parameters of a rotating shaft significantly. Furthermore, the dynamic unbalance effect on the response of a rotating shaft has also been studied in this thesis. Results indicate that the position of the unbalance is quite sensitive to the response of a rotating shaft. The sensitivity of unbalance and its position is dependent on the operation mode correspondence to the driving speed. The measured results indicate the dual-point measurement is quite available to study the dynamic responses of a rotating shaft or rotor.