In this paper, a theoretical model for vibrational predissociation (VP) of molecular clusters via intermediate states is proposed. It is shown that molecular intermediate states play an important role in inducing VP processes of molecular clusters. Based on this theory, a statistical dynamics model is established to describe and interpret qualitatively and semiquantatively the experimental line-broadening effects in various molecular clusters. Finally, we discuss the effects of a variety of coupling mechanisms on the energetic structures and the state relaxation processes in molecular clusters.