A fullwave analysis method of ultra-short pulse photoconductive switches is described in this paper.Three-dimension Maxwell curl equations

including the conductive current components

are solved using a Finite-Difference Time-Domain scheme.The influence of the static electric field on boundary condition is taken into account in the analysis.And a more reasonable photoconductive mathematical model is employed here.The constituent of switch output

influence of laser pulse energy and width upon the switch performance and the responses of three-dimension field pattern in switch at different time are presented.