The invention discloses a single-tube high-gain direct-current voltage enhancement conversion circuit with additional electric potential excitation, and belongs to the technical field of an electric power conversion circuit. According to the single-tube high-gain direct-current voltage enhancement conversion circuit with the additional electric potential excitation, charging and discharging of a voltage boosting inductance element and a parallel auxiliary inductance element are controlled by a single switching tube; an auxiliary capacitor is charged by the parallel auxiliary inductance element to form additional electric potential; the additional electric potential and a power supply voltage jointly perform superposition excitation to a voltage boosting inductor in the switch-on process of the switching tube, so that the voltage boosting inductor can obtain more electric energy; when the switching tube is switched off, a pump lifting voltage formed by the voltage boosting inductor can realize higher improvement of an input direct current voltage, so that output voltage gain which is much higher than that of a single-stage voltage boosting chopping wave conversion circuit can be obtained; and meanwhile, the circuit is simple in control modal state, and high in circuit power transferring efficiency, so that the circuit is applicable to enhancement and control of an output voltage of a photovoltaic battery of a photovoltaic power generation system.