A charge pump regulator at least includes a first charge pump circuit and a second charge pump circuit. In an enabled period, a first clock signal is provided to the first charge pump circuit. Consequently, the first charge pump circuit generates an output voltage to an output terminal of the charge pump regulator. In the enabled period, a second clock signal is provided to the second charge pump circuit. Consequently, the second charge pump circuit generates the output voltage to the output terminal of the charge pump regulator. In a first time interval of the enabled period, the first clock signal has a first frequency and the second clock signal is maintained at a fixed level. In a second time interval of the enabled period, both of the first clock signal and the second clock signal have a second frequency.