Potential and strength of surface electric field distribution have strongly influence on breakdown voltage and reliability of power semiconductor devices. Potential distribution can be determined by different field-limiting ring and field plate design which can be described by solving Poisson's equation in one dimension briefly. In this paper, the influence of design factors such as spacing between main junction and ring, ring width, and field plate width on potential and strength of surface electric field distribution are analyzed. From the simulation results, the relationship between those factors and potential and strength of surface electric field distribution can be found. Understanding the effect of design factors upon the junction termination edge, multi field-limiting rings and field plates of high breakdown power devices can be designed.