The invention discloses an open circuit detection system and method for a battery pack, relates to the technical field of battery fault detection, and aims at solving a problem that whether the battery pack is in an open circuit state cannot be accurately detected in the prior art. The system comprises a main processor, a bus voltage sampling circuit, a battery pack current sampling circuit, a communication module and an alarm module, wherein a first port of the main processor is connected to the bus voltage sampling circuit; a second port of the main processor is connected to the battery packcurrent sampling circuit; a third port of the main processor is connected to the communication module; and a fourth port of the main processor is connected to the alarm module. According to the scheme, whether an open-circuit fault exists in the battery pack can be accurately detected and judged through the changes of a bus voltage and a current of the battery pack. The circuit is simple in structure, low in cost, convenient to operate and capable of judging whether the open-circuit fault exists in the battery pack through a simple circuit connection.