The stability of mold oscillation can directly influence on slab surface quality and operational safety in continuous casting. In recent years, the hydraulic oscillation is developed and applied as the driven equipment of mold oscillation. In the present work, based on the slab continuous caster of hydraulic oscillations, the displacement and other parameters of hydraulic oscillator are measured and the evaluation method of oscillation is studied. The displacement difference and phase difference of oscillation with sinusoidal waveform and non-sinusoidal waveform are analyzed. Especially, the dynamic characteristics of the driving force of left and right cylinders are evaluated. The results indicated that the hydraulic oscillator is quite a good device in terms of precision. The method proposed may be useful for evaluating oscillators.