Dielectric electroactive polymer (DEAP) cylindrical actuators have a simple structure and strong capability to output large displacements and forces. Analysis of its structural parameters forms the basis for its design optimization and proper operation of DEAP actuators. Through geometric modeling of the actuator, the impact of axial elongation and diameter-thickness ratio on the deformation of each layer was analyzed. Based on the failure mode analysis, the influence of actuator structure parameters of pre-stretch, winding number of the DEAP film, spring parameters, etc. on its performance was obtained. Results showed that small diameter-thickness ratio and large winding layers would change the film thickness difference significantly in each layer when the actuator was elongated. According to the structural features of cylindrical actuators, the main factors affecting the allowable scope of work were the failure modes of electric breakdown of DEAP film, the loss of actuating force of the compression spring, and extreme deformations. The actuators performed better when the pre-stretch was increased and the pre-stretch ratio in circumference was larger than that in axial. No significant effect was observed on the output performance by increasing the layer-number. Reducing the stiffness and length of the spring can increase the axial stretch ratio of the actuator, and it had variable impact on the axial displacement changes. Meanwhile, the calculated force difference should be prevented from exceeding the preloaded force of the spring.