The series resonant technology of TEA CO2 laser charging power supply is introduced. The working principle of the full bridge series resonant converter is mathematically analyzed. In the charging circuit, the relationship between the transient state, average charging currents and the parameters of the resonant components is derived. Using the integrated chip SG3525 and IR2110, the high efficiency and practical charging power supply to fit the high voltage and high power TEA CO2 laser is designed.