The invention relates to a quasi resonant flyback power supply and a high voltage starting circuit thereof. The high voltage starting circuit of the quasi resonant flyback power supply comprises a bidirectional TVS tube, a quasi resonant controller and a charging capacitor. According to the quasi resonant flyback power supply and the high voltage starting circuit thereof of the invention, current is started through constant high voltage so as to charge the charging capacitor of the quasi resonant controller, such that quick start of the quasi resonant controller can be realized; and the constant high voltage-started current can be cut off effectively after the start of the quasi resonant controller is realized, and therefore, the efficiency of the quasi resonant flyback power supply can be improved, and energy loss of a quasi resonant flyback power supply system when the quasi resonant flyback power supply is in a standby state can be decreased.