The stress-strain constitutive model for dielectric electroactive polymer (EAP) films is the basis for the design and optimization of EAP actuators. A nonlinear hyperelastic model of EAP film with a space network structure is proposed, which is composed of nonlinear springs. Based on the energy method, the equations of stress and deformation are derived, and the relationship between the hyperelastic model and Ogden model is also revealed. The model parameters are fitted through uniaxial and equi-biaxial experiment data, and then the models also used to forecast the tensile stresses of equi-biaxial and uniaxial tests, and the results are compared and analyzed. There exist discrepancies between the predicted results and test data when using the models to forecast tests which parameters fitted under different experiment conditions. Comprehensive fitting method is presented for uniaxial and biaxial tensile experiment data, and then the analysis precision greatly improved. The results show that, under two experiment conditions, the 3-parameters nonlinear hyperelastic model can accurately describe the relationship of stress and displacement of EAP films, and the model parameters should acquire through the experiments similar to work conditions.