A power adapter, comprising: a full-bridge rectification circuit, configured to rectify an input alternating current and output a voltage of a first pulsating waveform; and a switch unit, configured to modulate the voltage of the first pulsating waveform according to a control signal; a transformer, configured to output a voltage of a second pulsating waveform based on the voltage of the modulated first pulsating waveform, wherein the full-bridge rectification circuit is connected to a primary winding of the transformer without electrolytic capacitor; a second rectification unit, configured to rectify the voltage of the second pulsating waveform and output a voltage of a third pulsating waveform; a first charging interface, coupled with the second rectification unit without electrolytic capacitor and configured to apply the voltage of the third pulsating waveform to a battery of a device via a second charging interface of the device when the first charging interface is coupled with the second charging interface, wherein the second charging interface is coupled with the battery; a sampling unit, configured to sample an output voltage of the second rectification unit; a control unit, coupled with the sampling unit and the switch unit respectively; the control unit being configured to output the control signal to the switch unit such that the sampling unit samples the voltage output from the second rectification unit such that the voltage sampling value is synchronized with the voltage of the first pulsating waveform; the control unit being further configured to adjust switch-on time and switch-off time of the switch unit according to the phase of the voltage of the first pulsating waveform such that phases of the voltage and current of the first pulsating waveform after modulation are the same thereby improving the power factor; the control unit being further configured to adjust the duty ratio of the control signal such that the voltage and current of the third pulsating waveform reach, respectively, a required charging voltage and charging current. a full-bridge rectification circuit, configured to rectify an input alternating current and output a voltage of a first pulsating waveform; and a switch unit, configured to modulate the voltage of the first pulsating waveform according to a control signal; a transformer, configured to output a voltage of a second pulsating waveform based on the voltage of the modulated first pulsating waveform, wherein the full-bridge rectification circuit is connected to a primary winding of the transformer without electrolytic capacitor; a second rectification unit, configured to rectify the voltage of the second pulsating waveform and output a voltage of a third pulsating waveform; a first charging interface, coupled with the second rectification unit without electrolytic capacitor and configured to apply the voltage of the third pulsating waveform to a battery of a device via a second charging interface of the device when the first charging interface is coupled with the second charging interface, wherein the second charging interface is coupled with the battery; a sampling unit, configured to sample an output voltage of the second rectification unit; a control unit, coupled with the sampling unit and the switch unit respectively; the control unit being configured to output the control signal to the switch unit such that the sampling unit samples the voltage output from the second rectification unit such that the voltage sampling value is synchronized with the voltage of the first pulsating waveform; the control unit being further configured to adjust switch-on time and switch-off time of the switch unit according to the phase of the voltage of the first pulsating waveform such that phases of the voltage and current of the first pulsating waveform after modulation are the same thereby improving the power factor; the control unit being further configured to adjust the duty ratio of the control signal such that the voltage and current of the third pulsating waveform reach, respectively, a required charging voltage and charging current.