The semiactive vibration control method based on synchronized switch damping (SSD) techniques has attracted much attention due to its simplicity and high efficiency. Switching of voltage on a piezoelectric patch can easily be rea lized by a simple circuit composed of a few electronic components. In this study the relationship between the switching delay and the control performance was in vestigated. The expressions of vibration damping of the synchronized switch damp ing on inductor (SSDI) and synchronized switch damping on voltage source (SSDV) were derived considering the switching delay time. In additional, the experiment al platform of semiactive vibration control for cantilever composite beam was e stablished, and the theoretical analysis was verified in the experiments. The re sults show that the better the control performance gets, the shorter the switchi ng delay is.