Abstract: The response of a nonlinear vibration system may be of three types, namely,periodic, quasiperiodic or chaotic. when foe parameters of foe system are changed. The periodic motions can be identified by Poincarb map, and harmonic wavelet transform(HAT) can distinguish quasiperiod from chaos, so the existing domains of differenttypes of motions of the system can be revealed in the parametric space with themethod of HWT joining with Poincare map.

Key words: wavelet transform, nonlinear vibration, bifurcation chaos