The invention relates to a system for monitoring a photovoltaic battery pack string and belongs to the field of running and management of a photovoltaic power generation system. In a photovoltaic power station, photovoltaic battery packs are connected in series and then are connected with a header box according to specific conditions, photovoltaic battery pack strings are connected in parallel, and the header box is connected with a grid-connected inverter. When the typical problems of connection, dust accumulation, component obsolescence difference and the like in a photovoltaic battery occur, the efficiency of the photovoltaic power generation system is influenced, and a monitoring system is needed to be arranged in the header box to monitor the photovoltaic battery pack string. The monitoring system can effectively manage the photovoltaic power station by acquiring photovoltaic pack string parameters, and combining other system parameters of the power station to realize autodiagnosis and effectively identify the problem of the power station. The system comprises a singlechip system, a power supply circuit, a voltage detection circuit, a current detection circuit, an intelligent communication interface circuit, an electrical meter chip and the like. In the system, a large-scale integrated circuit is used, and the system has a small volume, is low in energy consumption, has high reliability, and realizes the capacity of continuously monitoring the photovoltaic pack string in the life of the photovoltaic power generation system when assembled in the photovoltaic header box.