ObjectiveTo analyze the factors influencing the occurrence of subclinical leaflet thrombosis (SLT) after percutaneous aortic valve replacement using balloon-expandable valve (Sapien3, S3). Methods Retrospective analysis was made on 62 patients with severe aortic stenosis undergoing percutaneous aortic valve replacement using S3 in our center from September 2020 to June 2022. Patients with a history of vascular atherosclerosis or with significant increase or insignificant decrease of aortic valve flow or gradient pressure during follow-up were selected for CT examination. Results A total of 26 patients were finally included, with an average age of 70.31±8.90 years, and the male proportion was higher (n=15, 57.69%). Among them, 5 patients had SLT. Compared with the non-SLT group, patients in the SLT group were older (68.52±8.80 years vs. 77.80±4.66 years, P=0.007). The age factor (≥75 years) and the diameter of the ascending aorta were associated with SLT (both P<0.05). Conclusion The incidence of SLT is higher in the elderly patients. It is speculated that SLT is related to the characteristics of short balloon dilation valves and low blood flow dynamics of valve racks.