The present invention discloses a charging device, a charging method, a power supply adapter and a terminal. The charging device comprises: a charging receiving terminal configured to receive alternating current electric supply; a voltage regulation circuit comprising a first rectification unit, a switching unit, a transformer and a second rectification unit, wherein the first rectification unit is configured to perform rectification of the alternating current electric supply to output a voltage with a first ripple waveform, the switching unit is configured to modulate the voltage with the first ripple waveform according to the control signals, the transformer outputs a voltage with a second ripple waveform according to the modulated voltage with the first ripple waveform, the second rectification unit is configured to perform rectification of the voltage with the second ripple waveform to output a voltage with a third ripple waveform, and the voltage regulation circuit is configured to directly load the voltage with the third ripple waveform to a battery; and a central control module configured to output the control signals to the switching unit to regulate a voltage and/or a current output by the voltage regulation circuit and respond to charging demands of the battery. Therefore, the rapid charging of the battery is achieved, and the service life of the battery is improved.