Charging current control method and charging system

A charging method and a charging system are introduced for controlling a charging current by a PWM method. A charging IC (300) is controlled to supply the charging current to a battery (400), and a control unit (100) is used to generate a PWM signal with a duty cycle, and a filter unit (200) is used to convert the PWM signal into a voltage signal to be supplied to the charging IC, and the control unit determines whether a current of a battery detected by the battery status detection unit reaches a regular current, so that a PWM signal with a duty cycle greater than the previous duty cycle by a default increased cycle is provided if the detected current has not reached the regular current. Thus, the feature of the PWM signal is used to set the charging current according to the capacity of the battery automatically.