Abstract: Aiming at the issues of elastic resonance and cogging torque disturbance in the two-mass transmission system of CNC feed drives, this paper conducts research on dynamic modeling of two-mass flexible transmission, mechanical resonance mechanism, as well as vibration suppression methods based on notch filters and Luenberger observers. An equivalent two-mass dynamic model is established to analyze the resonance law of the system. Combined with the stiffness of the elastic shaft and the inertias of the motor and load, the natural resonant frequencies under multiple load conditions are quantitatively calculated. Single-frequency and dual-frequency narrowband notch structures are constructed, the amplitude-phase characteristics of the filters are analyzed, and the output terminal of the speed PI controller is identified as the optimal embedding position. Electromechanical simulations preliminarily verify the vibration suppression performance of the filters. A multi-load torsional test bench and a ball screw feed test bench are built for frequency sweep experiments. The single-frequency notch filter can suppress single resonance at fixed frequency points, while the dual-frequency structure attenuates two-order modes simultaneously without impairing dynamic characteristics in other frequency bands. A fifth-order Luenberger speed observer is adopted to suppress time-varying cogging disturbances, which predicts and corrects motion states based on the dynamic model. Experimental results prove that the observer can attenuate cogging harmonic ripples across the full speed range without parameter retuning with rotational speed changes. The two vibration suppression schemes eliminate fixed-frequency elastic resonance and time-varying cogging disturbances respectively. The corresponding analytical and experimental conclusions can offer theoretical references for improving the operation performance of servo feed systems and expanding the closed-loop control bandwidth.