The zero-current switching resonant switched capacitor DC-DC converter is a new type of power converter, which has features of low weight, small volume, high efficiency, low EMI and feasibility of fabrication on a semiconductor IC chip. In this study, we focus on the parametric analysis of a double-mode resonant switched capacitor converter proposed by Cheng in 1998. Since there exists great performance differences between ideal model and real circuit, in this work we propose a modified model by adding the resistance of circuit components. The modified model is then employed to study the circuit performance with respect to the loading effect and the variation of circuit parameters. Simulation results were found to be nearly in accordance with Cheng's experiment. In the paper, the average output voltage is explicitly expressed in terms of the so-called live time ratio, which provides a means of regulating the converter's output voltage.