The traditional medium and small power twelvephase synchronous generatorrectifier had a low voltage level, and its rectifying device was usually composed of four sets of parallel uncontrolled rectifier units. With the development of medium voltage DC integrated power technology for ship, the capacity of the generation system and the voltage level were greatly improved. The rectification unit adopted twoparalleltwoseries topology to avoid excessive voltage design value of the generator winding, and the rectifying terminal neutral line could lead to the equalization control for the electric propulsion speed regulating device. So the topology was gradually adopted. The different connection combinations of twoparalleltwoseries topologies were analyzed. The DCside voltage waveforms under two feasible topologies were analyzed and calculated. The correctness of theoretical analysis was verified by simulation and experiment. The (Y1//Y3)+(Y2//Y4) topology was the optimal combination with the best DC voltage quality.