The photovoltaic combiner box can reduce the connection of the photocell array to the inverter. It is one of the basic devices for the normal operation of the photovoltaic power plant. The junction box equipment using the Hall sensor cannot meet the requirements of the photovoltaic power generation system when the ambient temperature changes greatly. In this paper, a photovoltaic current sinking device based on high-accuracy fluxgate sensor, hall current sensor and low-power single-chip PIC16F1947 is designed to overcome this defect. In order to improve the current measurement accuracy, this paper also proposes a two-point successive interpolation correction method based on least squares method. Finally, experiments carried out verify the effectiveness of the proposed design and method.