In this study the string vibration of the moving silent chain is discussed experimentally. It is found there are two kinds of string vibration occurred in a moving silent chain: one has the same frequency with meshing between chain and sprocket and another has the frequency that equals 1/2 of meshing frequency. The former is the resonant vibration excited by the meshing, but the later is the parametrically-excited vibration caused by the fluctuation of chain tension.