Abstract: Electromechanical stability of the DE actuator is one of the important indexes to measure the dielectric elastomer properties. Simulation calculation and theoretical modeling are adopted to investigate the electromechanical stability of the DE actuator. Based on Neo-Hookean strain energy function and the theory that at the equilibrium state the Hessian Matrix to the free energy function of the system must be positive definite, an electrostrictive strain model of the DE actuator with uniaxial pre-stretch is established. The equilibrium equations describing the relations of input and output are derived. The behaviour of the actuator with uniaxial pre-stretch and the voltage are simulated by ABAQUS as well. The simulation results agree well with the analytic results. And the equilibrium equations obtained and the method used in the FEM can be used in the design of DE actuators.