Adapter, electronic device and charging method thereof

The invention provides an adapter, an electronic device and a charging method thereof. The electronic device comprises a USB interface unit, a temporary storage unit and a control unit, wherein the USB interface unit is provided with a D+ pin and a D- pin; the temporary storage unit is electrically connected to the USB interface unit; the control unit is used for controlling the temporary storage unit to transmit high-level voltage to the D+ pin, and reading the voltage level of the D+ pin and the D- pin after a specified time interval, wherein when the voltage level of the D+ pin and the D- pin read by the temporary storage unit is high-level voltage, the control unit controls the electronic device to be switched into an adapter charging mode. Due to the special adapter, the electronic device can automatically change the charging mode without wire replacement, and the convenience and portability brought to a user are improved.