In order to realize the optimal coordination of trajectory tracking and lateral stability of emergency rescue vehicles, a vehicle nonlinear parallel control method based on Hamiltonian function is proposed. The vehicle dynamics model and trajectory tracking model are established respectively, the vehicle dynamics model and trajectory tracking model are expressed as state equations with the same control input through model transformation, thus, the trajectory tracking and lateral stability coordinated control problem is transformed into a class of nonlinear parallel control problem. The Hamiltonian functions of trajectory tracking control and lateral stability control are designed respectively, and the existence conditions of controller design based on vehicle characteristics are discussed and proved, then, a nonlinear parallel control method considering the trajectory tracking and lateral stability control performance of emergency rescue vehicles is proposed, and the stability of control system is proved. The results show that, the trajectory tracking accuracy and stability control accuracy under the parallel control are increased by 10. 13% and 13. 79% respectively, which verifies that the designed method can better realize the coordinated control of trajectory tracking and lateral stability for emergency rescue vehicle.