Based on experiment modal analysis (EMA) and operation modal analysis (OMA), the dynamic characteristics of cylindrical grinding machine were measured and provided a basis for further failure analysis. The influences of grinding parameters on dynamic characteristics were studied by analyzing the diagnostic signals extracted from racing and grinding experiments. The significant frequency of 38 Hz related to grinding wheel spindle speed of 2 307 r/min showed that the wheel spindle system was in a state of imbalance. And wheel rotating frequency of 38.45Hz in grinding process was close to the first natural frequency of 38 Hz, which resulted in resonance. Moreover, the main excitation at 147 Hz in grinding process together with resonance led to the deterioration of workpiece. Roundness measurement of workpiece shows good agreement with the vibration responses obtained from dynamic experiments. The fault diagnosis method was also applicable to similar machining systems.