We elaborate the transit among all oscillations that the Wang model can exhibit,and explain a bistable region how to appear and disappear again.Especially,mixed-mode oscillations are important phenomena to which we devote ourselves in this paper.By reducing the four-dimensional Wang model to a two-dimensional model and making use of dynamical properties of critical manifold,we find the mixed-mode oscillations in the Wang model are closely related to canard explosion,and the unstable equilibriums on the repelling slow manifold play a key role in the pattern of mixed-mode oscillations.