The present disclosure relates to a saccular cavopulmonary assist device, including a shell, an inflow tube (6) and an outflow tube (4), wherein a blood storage cavity (A) and a power cavity (B) are arranged in the shell, and the power cavity (B) is used for providing contraction and relaxation power for the blood storage cavity (A)； the inflow tube (6) is arranged at a position corresponding to the power cavity (B) on the shell, an outer end is used for communicating with the vena cava, and an inner end communicates with the blood storage cavity (A) after passing through the power cavity (B)； the outflow tube (4) is arranged at a position corresponding to the blood storage cavity (A) on the shell, an outer end is used for communicating with the pulmonary artery, and an inner end communicates with the blood storage cavity (A). This device can assist the cavopulmonary circulation of the single ventricle, realize repeated blood drawing and pumping actions, provide the required power for the pulmonary circulation of the patient, and restore the biventricular blood flow in the human body； and because the arrangement of the inflow tube in the power cavity, the internal structure of this device is more compact, the overall shape is smaller, and the energy of the power cavity can be fully utilized.
