A new analytical method to design the multiple floating field limiting rings (MFFLRs) system of power devices has been proposed in this paper. This analytic method starts from our previous single field limiting theory, extending to predict the MFFLRs's electric field and voltage distribution between multiple rings. Based on this method result, the effects of the junction depth and ring spacing on the voltage and edge field profile have been analyzed. A new simple procedure to predict the optimal spacing and the maximum breakdown voltage has also been presented. The excellent agreement with experimental and numerical analysis proves the applicability of the method presented in optimization of the MFFLRs of the power devices. (c) 2006 Elsevier Ltd. All rights reserved.