A power bank charging system, comprising: a power bank device, comprising: a first power pin (VBUS1), a first ground pin, a first data transmission pin (D1-), a second data transmission pin (D1+); a first diode coupled between the first power pin (VBUS1) and the first data transmission pin (D1-), wherein an anode of the first diode coupled to the first data transmission pin (D1-) and a cathode coupled to the first power pin (VBUS 1); and a battery coupled to the first power pin (VBUS1) and the first ground pin and coupled to the first data transmission pin (D1-) through the first diode, wherein the second data transmission pin (D1+) is short-circuited to the first ground pin, and the battery is configured to receive the charging current from the first power pin (VBUS1) and the first diode and thus is charged; and a transformer, comprising: a second power pin (VBUS2), a second ground pin, a third data transmission pin (D2-), a fourth data transmission pin (D2+); a power converter coupled to the third data transmission pin (D2-), the fourth data transmission pin (D2+) and the second ground pin, wherein the fourth data transmission pin (D2+) is short-circuited to the second ground pin, and the power converter is configured to enable AC power to undergo AC/DC conversion, so as to provide the charging current to the second power pin (VBUS2) and the third data transmission pin (D2-); and a second diode coupled between the power converter and the second power pin (VBUS2), wherein an anode of the second diode coupled to the power converter and a cathode coupled to the second power pin (VBUS2); and wherein the power bank device is connectable to the transformer. a power bank device, comprising: a first power pin (VBUS1), a first ground pin, a first data transmission pin (D1-), a second data transmission pin (D1+); a first diode coupled between the first power pin (VBUS1) and the first data transmission pin (D1-), wherein an anode of the first diode coupled to the first data transmission pin (D1-) and a cathode coupled to the first power pin (VBUS 1); and a battery coupled to the first power pin (VBUS1) and the first ground pin and coupled to the first data transmission pin (D1-) through the first diode, wherein the second data transmission pin (D1+) is short-circuited to the first ground pin, and the battery is configured to receive the charging current from the first power pin (VBUS1) and the first diode and thus is charged; and a first power pin (VBUS1), a first ground pin, a first data transmission pin (D1-), a second data transmission pin (D1+); a first diode coupled between the first power pin (VBUS1) and the first data transmission pin (D1-), wherein an anode of the first diode coupled to the first data transmission pin (D1-) and a cathode coupled to the first power pin (VBUS 1); and a battery coupled to the first power pin (VBUS1) and the first ground pin and coupled to the first data transmission pin (D1-) through the first diode, wherein the second data transmission pin (D1+) is short-circuited to the first ground pin, and the battery is configured to receive the charging current from the first power pin (VBUS1) and the first diode and thus is charged; and a transformer, comprising: a second power pin (VBUS2), a second ground pin, a third data transmission pin (D2-), a fourth data transmission pin (D2+); a power converter coupled to the third data transmission pin (D2-), the fourth data transmission pin (D2+) and the second ground pin, wherein the fourth data transmission pin (D2+) is short-circuited to the second ground pin, and the power converter is configured to enable AC power to undergo AC/DC conversion, so as to provide the charging current to the second power pin (VBUS2) and the third data transmission pin (D2-); and a second diode coupled between the power converter and the second power pin (VBUS2), wherein an anode of the second diode coupled to the power converter and a cathode coupled to the second power pin (VBUS2); and a second power pin (VBUS2), a second ground pin, a third data transmission pin (D2-), a fourth data transmission pin (D2+); a power converter coupled to the third data transmission pin (D2-), the fourth data transmission pin (D2+) and the second ground pin, wherein the fourth data transmission pin (D2+) is short-circuited to the second ground pin, and the power converter is configured to enable AC power to undergo AC/DC conversion, so as to provide the charging current to the second power pin (VBUS2) and the third data transmission pin (D2-); and a second diode coupled between the power converter and the second power pin (VBUS2), wherein an anode of the second diode coupled to the power converter and a cathode coupled to the second power pin (VBUS2); and wherein the power bank device is connectable to the transformer.