The dynamical characteristic of a periodical fast switch valve was investigated theoretically and by experiments. It has been found that the pressure transient created by the periodic valve switching has different features with those of one closure. Except for the flow velocity and the closure speed, the switching frequency influences greatly the intensity of pressure transient. To gain the insight into the fluid dynamic performance inside the hydraulic system, the nonlinear resonance initiated by the interaction of succeeding pressure transients has to be taken into consideration. The numerical obtained results also agree well with the measured one. The used simulation model therefore will be useful in further developmental work.