A novel single-sensor method for monitoring rotating blade vibration is proposed and utilized to identify vibration parameters under the non-stationary condition. By analyzing the pulse-signal waveform, the blade tip displacement and vibration velocity are extracted. Then, the motion equation under the non-stationary condition is further developed to provide a theoretical basis. Finally, the optimization technology is applied to extract vibration parameters. Compared with multiple-sensor methods, the proposed method has lower installation difficulty, less equipment cost, fewer sensors, and no strict sensor layout requirement. Numerical simulations and experiments are conducted to validate the effectiveness and robustness of the proposed method. The relative error in the natural frequency does not exceed 0.1 %. Additionally, errors in other parameters are less than 8 % in the experiment.