Based on the exciting technology of excimer laser used for semiconductor lithography, the charging process of pulse transformer is analyzed using the Laplace formula. It is validated that the coupling factor influences the charging time. The charging time is compressed when the coupling factor is close to 1 The discharge process of charging circuit combined with magnetic switches is introduced. A scheme for controlling the resonant charging is also proposed. The power supply designed can fulfi11 the charge process in 50μs