A power supply system for an electric vehicle, comprising: a battery system comprising a plurality of battery packs (B1, BN) connected in parallel which is/are controlled by a Battery Management System to be connected to and disconnected from a high-voltage DC bus of the electric vehicle, wherein the battery system is configured to power the electric vehicle; a range extender configured to generate a DC current so as to charge the battery system and power the electric vehicle; and a controller configured to control a power generating mode of the range extender, to control a connection status of each battery pack (B1, BN) with the high-voltage DC bus of the electric vehicle, and to control a connection status of the range extender with the high-voltage DC bus of the electric vehicle; characterized in that, the power supply system further comprising a plurality of switches comprising a first switch (S1+, SN+) and a second switch (S1-, SN-) provided respectively for each battery pack (B1, BN), wherein the first switch (S1+, SN+) being arranged between a respective battery pack (B1, BN) and the high-voltage DC bus, one end of the second switch (S1-, SN-) being connected to the range extender, and the other end of the second switch (S1-, SN-) being connected to a respective battery pack (B1, BN) and the first switch (S1+, SN+) connecting said battery pack (B1, BN) at a position between said battery pack (B1, BN) and said first switch (S1+, SN+), and for each of the plurality of battery packs (B1, BN) connected in parallel, when the first switch (S1+, SN+) connected to the battery pack (B1, BN) is switched on and the second switch (S1-, SN-) connected to the battery pack (B1, BN) is switched off, the battery pack (B1, BN) is configured to power the electric vehicle; when the first switch (S1+, SN+) connected to the battery pack (B1, BN) is switched off and the second switch (S1-, SN-) connected to the battery pack (B1, BN) is switched on, the range extender is configured to charge the battery pack (B1, BN); and when the first switch (S1+, SN+) and the second switch (S1-, SN-) connected to the battery pack (B1, BN) are switched on, the range extender and the battery pack (B1, BN) are configured to power the electric vehicle simultaneously. a battery system comprising a plurality of battery packs (B1, BN) connected in parallel which is/are controlled by a Battery Management System to be connected to and disconnected from a high-voltage DC bus of the electric vehicle, wherein the battery system is configured to power the electric vehicle; a range extender configured to generate a DC current so as to charge the battery system and power the electric vehicle; and a controller configured to control a power generating mode of the range extender, to control a connection status of each battery pack (B1, BN) with the high-voltage DC bus of the electric vehicle, and to control a connection status of the range extender with the high-voltage DC bus of the electric vehicle; characterized in that, the power supply system further comprising a plurality of switches comprising a first switch (S1+, SN+) and a second switch (S1-, SN-) provided respectively for each battery pack (B1, BN), wherein the first switch (S1+, SN+) being arranged between a respective battery pack (B1, BN) and the high-voltage DC bus, one end of the second switch (S1-, SN-) being connected to the range extender, and the other end of the second switch (S1-, SN-) being connected to a respective battery pack (B1, BN) and the first switch (S1+, SN+) connecting said battery pack (B1, BN) at a position between said battery pack (B1, BN) and said first switch (S1+, SN+), and for each of the plurality of battery packs (B1, BN) connected in parallel, when the first switch (S1+, SN+) connected to the battery pack (B1, BN) is switched on and the second switch (S1-, SN-) connected to the battery pack (B1, BN) is switched off, the battery pack (B1, BN) is configured to power the electric vehicle; when the first switch (S1+, SN+) connected to the battery pack (B1, BN) is switched off and the second switch (S1-, SN-) connected to the battery pack (B1, BN) is switched on, the range extender is configured to charge the battery pack (B1, BN); and when the first switch (S1+, SN+) and the second switch (S1-, SN-) connected to the battery pack (B1, BN) are switched on, the range extender and the battery pack (B1, BN) are configured to power the electric vehicle simultaneously.