A current-voltage curve scanning method for a photovoltaic string, wherein the method is applied to converters in a photovoltaic power generation system, an input end of each converter is connected to one photovoltaic string, each converter is configured to control an output voltage of the connected photovoltaic string; and the method comprises: obtaining output powers at initial scan points of photovoltaic strings in a first group, and obtaining output powers at initial scan points of photovoltaic strings in a second group; characterized in that the method further comprises: controlling the output powers at the initial scan points of the photovoltaic strings in the first group to sequentially decrease, and controlling the output powers at the initial scan points of the photovoltaic strings in the second group to sequentially increase, wherein an initial scan direction of each photovoltaic string in the first group is a direction in which an output voltage changes as an output power decreases, and an initial scan direction of each photovoltaic string in the second group is a direction in which an output voltage changes as an output power increases; and performing current-voltage IV curve scanning on the first group in the initial scan direction of the first group starting from output voltages corresponding to the output powers at the initial scan points of the first group, and performing current-voltage IV curve scanning on the second group in the initial scan direction of the second group starting from output voltages corresponding to the output powers at the initial scan points of the second group, wherein output powers of the first group and the second group are kept to compensate each other during IV curve scanning. obtaining output powers at initial scan points of photovoltaic strings in a first group, and obtaining output powers at initial scan points of photovoltaic strings in a second group; characterized in that the method further comprises: controlling the output powers at the initial scan points of the photovoltaic strings in the first group to sequentially decrease, and controlling the output powers at the initial scan points of the photovoltaic strings in the second group to sequentially increase, wherein an initial scan direction of each photovoltaic string in the first group is a direction in which an output voltage changes as an output power decreases, and an initial scan direction of each photovoltaic string in the second group is a direction in which an output voltage changes as an output power increases; and performing current-voltage IV curve scanning on the first group in the initial scan direction of the first group starting from output voltages corresponding to the output powers at the initial scan points of the first group, and performing current-voltage IV curve scanning on the second group in the initial scan direction of the second group starting from output voltages corresponding to the output powers at the initial scan points of the second group, wherein output powers of the first group and the second group are kept to compensate each other during IV curve scanning. controlling the output powers at the initial scan points of the photovoltaic strings in the first group to sequentially decrease, and controlling the output powers at the initial scan points of the photovoltaic strings in the second group to sequentially increase, wherein an initial scan direction of each photovoltaic string in the first group is a direction in which an output voltage changes as an output power decreases, and an initial scan direction of each photovoltaic string in the second group is a direction in which an output voltage changes as an output power increases; and performing current-voltage IV curve scanning on the first group in the initial scan direction of the first group starting from output voltages corresponding to the output powers at the initial scan points of the first group, and performing current-voltage IV curve scanning on the second group in the initial scan direction of the second group starting from output voltages corresponding to the output powers at the initial scan points of the second group, wherein output powers of the first group and the second group are kept to compensate each other during IV curve scanning.