A battery pack and a battery system are provided. The battery pack includes at least one housing, a battery, and at least one liquid cooling plate. The at least one housing defines an accommodating space for accommodating an immersion liquid and includes a first end portion and a second end portion arranged opposite to the first end portion. The first end portion defines a first liquid inlet, and the second end portion defines a first liquid outlet. The battery is arranged in the accommodating space. The at least one liquid cooling plate is adjacent to and connected to the at least one housing and configured to accommodate a cooling liquid, and the at least one liquid cooling plate includes a third end portion and a fourth end portion arranged opposite to the third end portion. The third end portion defines a second liquid outlet, and the fourth end portion defines a second liquid inlet. The first end portion is adjacent to and connected to the third end portion, and the second end portion is adjacent to and connected to the fourth end portion. The battery pack can enhance heat dissipation efficiency. Figure 1