GMHPUT has a wide range of potential application in industrial. However, nonlinearity between exciting current and output displacement spoils GMHPUT’s performance. To explore the nonlinearity behaviors of GMHPUT, a nonlinear dynamic model was established. The bifurcation diagrams, phase portrait, Poincaré mapping diagrams, amplitude spectrum, Lyapunov exponent, etc. which demonstrate dynamical characteristics of the system were obtained by numerical integration. Analysis indicates: Nonlinearity of response could be improved by increasing of damping coefficient. Chaos would appear when stiffness of the system is low. At last experiments were done to verify the model. Calculation results and experimental results show a good agreement.