Energy harvesting using Dielectric Electroactive Polymer (DEAP) is an interesting possibility to convert mechnical energy to electrical energy. The fundamental of generator mode of DEAP is first described, and then an equivalent RC electrical model for the DEAP generator is given. Based on the RC model, we analyze the relationship between the electrical model parameters and the influencing factors, and then get their theoretical formulas. In the experiment, the annular type DEAP generator unit is used. Using the discharging method, the experimental data about the electrical parameters influenced by the applied voltage and the axial displacement are obtained respectively. We modify the theoretical formulas based on the experimental data. The modified formuals can serve as a significant guide for energy conversion and generator design using dielectric elastomer.