The invention discloses a self-coupling direct-current converter and a control method thereof. The self-coupling direct-current converter consists of a plurality of bridge type structures, the self-coupling direct-current converter is of longitudinal symmetry and is grounded in the middle, and a positive pole and a negative pole exist due to output. The bridge type structure can be of a diode clamping type half-bridge structure, or a half-bridge structure or a full-bridge structure. Two large inductors with equal inductance are arranged at a low-voltage side input end, the two inductors can also be merged into one inductor to be arranged at the position of the positive pole of the low-voltage side input end. Small inductors with equal inductance are arranged at two ends of the positive pole and the negative pole of a high-voltage side output end respectively. The control method of the self-coupling direct-current converter adopts a phase-shift PWM mode to control the access and bypass of the bridge type structure, and the stability of output voltage is controlled through a current voltage double closed loop. According to the self-coupling direct-current converter and the control method of the self-coupling direct-current converter provided by the invention, in the electric energy conversion process, the energy loss is low, the switch loss is low, and the self-coupling direct-current converter has the characteristics of high transformation ratio, small volume, high voltage resistance and high capacity.