The results of this paper provide the theoretic foundation for locating partial discharge source precisely and makes up for the shortage of TEV. Finite-difference time-domain method（FDTD）is used to simulate the TEV signal on switchgear and precise location method is studied with four channel detection system. Research shows that using hyperboloid method and spatial grid search method can locate the PD source precisely. Furthermore

an optimization method which is used to estimate the equivalent pulse width and amplitude of Gaussian pulse source for simulating PD of switchgear is presented by combining the simulated annealing algorithm with the FDTD method. It can provide theoretical basis for calculating the real intensity of PD signal and switchgear insulation condition assess accurately with a new perspective.