A wireless charging circuit and an abnormal state protection circuit thereof is provided in the present invention. The wireless charging circuit includes a power converter, a resonant circuit and an abnormal state protection circuit. The power converter receives an input voltage for outputting a PWM (pulse width modulation) signal. The input terminal of the resonant circuit receives the PWM signal. The common voltage terminal of the resonant circuit is coupled to a common voltage. The abnormal state protection circuit includes a DC sampling circuit and a control circuit. The DC sampling circuit is coupled to the resonant terminal of the resonant circuit for sampling the DC component of the voltage of the resonant terminal to obtain a DC voltage. The control circuit is coupled to the power converter and the DC sampling circuit for receiving the DC voltage. When the DC voltage is greater than a threshold voltage, the control circuit controls the power converter to reduce the current flowing through the resonant circuit.