A string inverter control method, wherein a string inverter comprises one or more first direct current/direct current step-up circuits, one or more second direct current/direct current step-up circuits, and an inverter circuit, wherein output ends of the first direct current/direct current step-up circuits and the one or more second direct current/direct current step-up circuits are connected in parallel and then connected to an input end of the inverter circuit, wherein the one or more first direct current/direct current step-up circuits are direct current/direct current step-up circuits on which current-voltage IV curve scanning is performed, the one or more second direct current/direct current step-up circuits are direct current/direct current step-up circuits on which the IV curve scanning is not performed, and the method is characterized by: in a process of performing the IV curve scanning on the one or more first direct current/direct current step-up circuits, controlling output power of the inverter circuit to be reference power, and controlling a change of an output voltage of the one or more second direct current/direct current step-up circuits, wherein a change trend of the output voltage of the one or more second direct current/direct current step-up circuits and a change trend of an input voltage of the one or more first direct current/direct current step-up circuits in the IV curve scanning process present a non-strictly monotonically increasing relationship, wherein the controlling a change of an output voltage of the one or more second direct current/direct current step-up circuits comprises: for any second direct current/direct current step-up circuit in the one or more second direct current/direct current step-up circuits, adjusting an actual value of an output voltage of the second direct current/direct current step-up circuit at each moment based on a reference value of the output voltage at the same moment, until an absolute value of a difference between the actual value of the output voltage of the second direct current/direct current step-up circuit at each moment and the reference value of the output voltage at the same moment is less than a difference threshold, wherein a change trend of reference values of output voltages of the second direct current/direct current step-up circuit at all moments in the IV curve scanning process and a change trend of input voltages of the one or more first direct current/direct current step-up circuits at all the moments in the IV curve scanning process present a non-strictly monotonically increasing relationship; wherein in the scanning process, as the input voltage of the one or more first direct current/direct current step-up circuits on which the IV curve scanning is performed decreases, the reference value of the output voltage of each of the second direct current/direct current step-up circuits on which the IV curve scanning does not need to be performed decreases or remains unchanged; wherein the output voltage of the second direct current/direct current step-up circuit also presents a decreasing trend. for any second direct current/direct current step-up circuit in the one or more second direct current/direct current step-up circuits, adjusting an actual value of an output voltage of the second direct current/direct current step-up circuit at each moment based on a reference value of the output voltage at the same moment, until an absolute value of a difference between the actual value of the output voltage of the second direct current/direct current step-up circuit at each moment and the reference value of the output voltage at the same moment is less than a difference threshold, wherein a change trend of reference values of output voltages of the second direct current/direct current step-up circuit at all moments in the IV curve scanning process and a change trend of input voltages of the one or more first direct current/direct current step-up circuits at all the moments in the IV curve scanning process present a non-strictly monotonically increasing relationship; wherein in the scanning process, as the input voltage of the one or more first direct current/direct current step-up circuits on which the IV curve scanning is performed decreases, the reference value of the output voltage of each of the second direct current/direct current step-up circuits on which the IV curve scanning does not need to be performed decreases or remains unchanged; wherein the output voltage of the second direct current/direct current step-up circuit also presents a decreasing trend.