A charging method, comprising following steps: performing a first rectification on an input alternating current to output a first voltage with a first pulsating waveform; performing a voltage conversion and a second rectification on the first voltage, to acquire a second voltage with a second pulsating waveform, and the second voltage being used to charge a battery in a terminal; controlling the voltage conversion according to a feedback from the terminal, to adjust a magnitude of the second voltage; being characterized by: communicating with the terminal to determine a charging mode, the charging mode comprising a first charging mode and a second charging mode, the second charging mode being configured to charge the battery in the terminal with the second voltage, the first charging mode being configured to charge the battery with a fourth voltage obtained by performing filtering on the second voltage; and when it is determined to charge the battery in the first charging mode, controlling a filter to perform the filtering on the second voltage to output the fourth voltage for charging the battery, wherein performing a voltage conversion and a second rectification on the first voltage to acquire a second voltage with a second pulsating waveform comprises: outputting a control signal to a switch unit to control the switch unit to modulate the first voltage and to output a modulated first voltage; controlling a transformer having a primary winding and a secondary winding, to output a third voltage with a third pulsating waveform according to the modulated first voltage; and controlling a second rectifier to perform a second rectification on the third voltage to output the second voltage, wherein the second pulsating waveform of the second voltage keeps synchronous with a waveform of the modulated first voltage. performing a first rectification on an input alternating current to output a first voltage with a first pulsating waveform; performing a voltage conversion and a second rectification on the first voltage, to acquire a second voltage with a second pulsating waveform, and the second voltage being used to charge a battery in a terminal; controlling the voltage conversion according to a feedback from the terminal, to adjust a magnitude of the second voltage; being characterized by: communicating with the terminal to determine a charging mode, the charging mode comprising a first charging mode and a second charging mode, the second charging mode being configured to charge the battery in the terminal with the second voltage, the first charging mode being configured to charge the battery with a fourth voltage obtained by performing filtering on the second voltage; and when it is determined to charge the battery in the first charging mode, controlling a filter to perform the filtering on the second voltage to output the fourth voltage for charging the battery, wherein performing a voltage conversion and a second rectification on the first voltage to acquire a second voltage with a second pulsating waveform comprises: outputting a control signal to a switch unit to control the switch unit to modulate the first voltage and to output a modulated first voltage; controlling a transformer having a primary winding and a secondary winding, to output a third voltage with a third pulsating waveform according to the modulated first voltage; and controlling a second rectifier to perform a second rectification on the third voltage to output the second voltage, wherein the second pulsating waveform of the second voltage keeps synchronous with a waveform of the modulated first voltage. communicating with the terminal to determine a charging mode, the charging mode comprising a first charging mode and a second charging mode, the second charging mode being configured to charge the battery in the terminal with the second voltage, the first charging mode being configured to charge the battery with a fourth voltage obtained by performing filtering on the second voltage; and when it is determined to charge the battery in the first charging mode, controlling a filter to perform the filtering on the second voltage to output the fourth voltage for charging the battery, wherein performing a voltage conversion and a second rectification on the first voltage to acquire a second voltage with a second pulsating waveform comprises: outputting a control signal to a switch unit to control the switch unit to modulate the first voltage and to output a modulated first voltage; controlling a transformer having a primary winding and a secondary winding, to output a third voltage with a third pulsating waveform according to the modulated first voltage; and controlling a second rectifier to perform a second rectification on the third voltage to output the second voltage, wherein the second pulsating waveform of the second voltage keeps synchronous with a waveform of the modulated first voltage. outputting a control signal to a switch unit to control the switch unit to modulate the first voltage and to output a modulated first voltage; controlling a transformer having a primary winding and a secondary winding, to output a third voltage with a third pulsating waveform according to the modulated first voltage; and controlling a second rectifier to perform a second rectification on the third voltage to output the second voltage, wherein the second pulsating waveform of the second voltage keeps synchronous with a waveform of the modulated first voltage.