After admission, the patient was given conventional treatment such as cardiac strengthening, diuretic, vasodilator and myocardial nutrition, and various tests were completed. After hospitalization, the patient continued to take long-term immunosuppressive drugs after renal transplantation, specifically Neostigmine (cyclosporine capsule) 50mg, twice a day, and Xiaoser (morte-macrolide) 0.25g, twice a day. After completing various examinations to clarify the diagnosis and indications for surgery and excluding contraindications to surgery, aortic valve replacement was performed under general anesthesia with tracheal intubation and hypothermic extracorporeal circulation. Intraoperative investigation (Figure C): left ventricular hypertrophy, double-phase tremor was detected in the aortic root, ascending aorta was widened, aortic valve with four leaves and four sinuses was arranged anteriorly and posteriorly, the leaflets were mildly thickened and calcified locally, the junction of the right anterior and right posterior coronary valves was mildly adherent, and the four leaves were incompatible and incompletely closed. One imported St. Jude 25 bioprosthetic flap was replaced and the operation went smoothly. On the preoperative day, Neosporin (cyclosporine capsule) 50mg and Xiaoser (morte-macrolide) 0.25g were given orally. Intraoperative methylprednisolone 500mg was given intravenously, and postoperative day intravenous fortification with 150mg for 3 consecutive days. On the 1st postoperative day, we continued to start Neosporin (cyclosporine capsule) 50mg, twice a day, and Xiaoser (morte-macrolide) 0.25g, twice a day. The tracheal intubation was removed on the 1st day after surgery, and the drainage tube was removed on the 3rd day. Postoperatively, routine antibiotics were given to prevent infection, and cardiac diuretic and vasodilator and anticoagulation treatments were given. Postoperative renal function was monitored daily, and no significant abnormalities in renal function indexes were found. The patient recovered smoothly with normal temperature and stable circulation, and no obvious rejection reaction was observed. Thirteen days after the operation, the blood routine and renal function were within the normal range, and the echocardiogram and cardiac plain film did not show any abnormality, and the incision was healed at grade I/A. The patient was discharged from the hospital. Aortic valve quadruple leaflet malformation is a very rare heart valve malformation. The normal aortic valve is composed of three semilunar valves, and the number and structural integrity of the valves are the anatomical basis for normal closure of the aortic valve. The incidence of aortic valve malformations is low, and there are usually unilobular, bilobular, and quadruple-lobe malformations. Bifid valves are relatively common, and unifid and quadrifid valves are extremely rare. Tetrafollicular malformation can be symmetrical or asymmetrical. The right anterior and right posterior valves are relatively small and have an overall field shape when closed, but they do not close together and have a markedly poor closure and open in an orifice shape with mild restriction. Congenital aortic quadrileaflet malformations are rarely combined with other congenital cardiac malformations, but can cause hemodynamic abnormalities by themselves, with an incidence of 44% [1], with aortic valve closure insufficiency being the most common, and aortic quadrileaflet malformations without hemodynamic abnormalities have no clinical symptoms and do not require management. If there is severe valve impairment, aortic valve replacement or angioplasty is required. In this case, the aortic quadruple valve malformation caused severe aortic valve closure insufficiency and mild stenosis, compensatory left ventricular hypertrophy, and impaired left ventricular function, and the patient had obvious clinical symptoms that were consistent with the indication for aortic valve replacement surgery. However, the patient had undergone renal transplantation 9 years ago and was taking immunosuppressive drugs for a long time after surgery, which increased the risk and difficulty of the operation. We suppressed immune rejection by giving 500 mg of methylprednisolone intravenously intraoperatively and 150 mg of methylprednisolone intravenously for three consecutive days after surgery, and also exerted its intraoperative anti-inflammatory and anti-allergic effects. In the case of intraoperative thin and brittle aortic vessel wall causing multiple bleeding, the analysis speculated that it was related to the patient’s long-term use of immunosuppressive drugs, and in this case the polyester sheet fixation wrapping around the aortic wall had a good effect of extensive compression to stop bleeding, which was confirmed intraoperatively and postoperatively. Patients with valve regurgitation and stenosis due to aortic quadruple leaflet malformation combined with post-renal transplantation have clear indications for surgery and are given valve replacement surgery. The occurrence of acute intraoperative and postoperative rejection can be avoided as long as the correct immune rejection drugs and hormones are given preoperatively and postoperatively [2]. The case of aortic valve quadruple leaflet malformation combined with post-renal transplantation has not been reported, and this case is of high reference significance for the implementation of aortic valve replacement in patients after renal transplantation and the response to perioperative immune rejection problems.