Abstract: The experiment driving the elastic swing to forced vibration by the electromagnetic vibration,and manipulating the phenomenon that small changes in capacitance value can produce a greater voltage drop on resistance in the RLC resonant circuit value（ small changes in the appropriate frequency range）,linking the elastic swing with the capacitance characteristics.Then we can get the relationship between the voltage changes and the change of elastic pendulum movement indirectly,and change the excitation frequency to study the amplitude frequency characteristic and phase frequency characteristic of the forced vibration.

Key words: forced non-contact elastic pendulum, electromagnetic vibration, RLC resonant circuit