Based on the Su-Schrieffer-Heeger (SSH) model extended to include the square term of the electron-lattice interaction，the dynamic characteristics of polarons are investigated. With increasing of the coefficient of the square term (β)，the energy gap between the valance band and the conduction band increases. but the total width of the energy band does not change. At the same time，it is found that the dimerization amplitude and the localization of polarons are strengthened by the nonlinear electron-lattice interaction. Furthermore，the results show that the polaron velocity is suppressed by the nonlinear electron-lattice interaction，and the critical electric field strength to dissociate the polaron increases with β increasing.