The invention relates to a laser excitation power supply and an excitation method thereof. The laser excitation power supply comprises a discharging main circuit, a sampling feedback control circuit and a weak current unit, wherein, the discharging main circuit comprises an anti-jamming filtering circuit, a power factor correcting unit, a power conversion unit and an IGBT discharging unit, which are electrically connected in sequence; the sampling feedback control circuit comprises a central control unit, a precombustion lighting unit and two electrical current sensors; the central control unit is respectively connected with the power factor correcting unit, the power conversion unit, the IGBT discharging unit, the precombustion lighting unit and the two electrical current sensors; the precombustion lighting unit is respectively connected with the power factor correcting unit, the IGBT discharging unit and the central control unit; electrical current output by the power factor correcting unit and the IGBT discharging unit is acquired by the two current sensors and transferred to the central control unit; and the central control unit judges the transferred electrical current, and controls the stable output of the power factor correcting unit and the IGBT discharging unit according to judged results. The invention improves the output power factor and the discharging stability.