A battery pack heating apparatus, applicable portably and externally to a vehicle, characterized in comprising: an electrical energy conversion component, comprising an energy storage device, a first set of switches and a second set of switches; a heating interface connected to the energy storage device via the first set of switches to form a first heating loop and connected to the energy storage device via the second set of switches to form a second heating loop, the heating interface being configured to be connected to a battery pack of one vehicle; and a heating control module configured to control a direction of electrical energy transfer between the battery pack and the energy storage device, wherein the heating control module is configured to control an on/off state of the first set of switches and an on/off state of the second set of switches, such that at least one heating sub-cycle is performed in a heating process for the battery pack until a predetermined heating condition is met, wherein in each heating sub-cycle, the heating control module is configured to close the first set of switches and switch off the second set of switches, such that a first electrical energy transfer is conducted between the energy storage device and the battery pack via the heating interface, and the heating control module is configured to switch off the first set of switches and switch on the second set of switches in response to a predetermined electrical energy transfer condition being met, such that a second electrical energy transfer is conducted between the energy storage device and the battery pack via the heating interface; wherein each of the first electrical energy transfer and the second electrical energy transfer is charging or discharging and the first electrical energy transfer and the second electrical energy transfer have different directions; and wherein the predetermined electrical energy transfer condition comprises a predetermined electrical energy transfer time length being reached, the predetermined electrical energy transfer time length comprising a discharging time length of the energy storage device and a charging time length of the energy storage device. an electrical energy conversion component, comprising an energy storage device, a first set of switches and a second set of switches; a heating interface connected to the energy storage device via the first set of switches to form a first heating loop and connected to the energy storage device via the second set of switches to form a second heating loop, the heating interface being configured to be connected to a battery pack of one vehicle; and a heating control module configured to control a direction of electrical energy transfer between the battery pack and the energy storage device, wherein the heating control module is configured to control an on/off state of the first set of switches and an on/off state of the second set of switches, such that at least one heating sub-cycle is performed in a heating process for the battery pack until a predetermined heating condition is met, wherein in each heating sub-cycle, the heating control module is configured to close the first set of switches and switch off the second set of switches, such that a first electrical energy transfer is conducted between the energy storage device and the battery pack via the heating interface, and the heating control module is configured to switch off the first set of switches and switch on the second set of switches in response to a predetermined electrical energy transfer condition being met, such that a second electrical energy transfer is conducted between the energy storage device and the battery pack via the heating interface; wherein each of the first electrical energy transfer and the second electrical energy transfer is charging or discharging and the first electrical energy transfer and the second electrical energy transfer have different directions; and wherein the predetermined electrical energy transfer condition comprises a predetermined electrical energy transfer time length being reached, the predetermined electrical energy transfer time length comprising a discharging time length of the energy storage device and a charging time length of the energy storage device.