© Published under licence by IOP Publishing Ltd. In this work, the influences of pre-stretch ratio on the electrical actuation performance of dielectric elastomer actuator (VHB 4905) are systematically investigated based on theoretical calculation and experimental tests. As the pre-stretch ratio increases, the maximum actuation strain increases at the initial phase, while decreases as pre-stretch ratio further increases. The peak value of actuation strain is attained when the electromechanical instability is just refrained by the pre-stretch, which is experimentally measured to be 3.25, with the maximum actuation strain of 90%.