In this paper

the new technique and the new boundary condition （Low Field Point--LFP） are introduced in the 2-D numerical simulation of the electrical field profiles of planar diodes with Floating Field Limiting Rings （FFLR’s） and Variation of Lateral Doping （VLD）. By making use of this technique

the breakdown characteristics of the diode with FFLR’s and VLD’s can be simulated correctly and speedily

if only Poisson’s equation is solved. To overcome the shortcome of low calculation efficiency at high voltage conditions

a new set of scaling factors

which are related to the maximun of the applied voltages

are introduced to scaling Poisson’s eqn. The empirical formula of the ratio of the scaling factor to the applied voltage is given. Finally

the planar diode with two FFLR’s and a VLD which is formed by the composed doping of five Gaussian type distributions are simulated respectively

and the correct distributions of the electrical field and the potential are obtained.