Management of tricuspid regurgitation( TR) before right ventricular dysfunction is critical in patients with hypoplastic left heart syndrome (HLHS);however, appropriate tricuspid valvuloplasty (TVP) is challenging. We report a TVP technique for TR in a 4-year-old girl with HLHS, who had undergone Norwood operation, bidirectional cavopulmonary shunt, and TVP. Preoperative echocardiography revealed the etiology of TR as anterior leaflet prolapse, annulus dilatation, and relative tethering of the septal leaflet. We performed surgical reconstruction of the anterior leaflet with artificial chordae. Before annuloplasty, the posterior leaflet and a part of the septal leaflet were detached from the annulus with a 1 mm margin using the Key-Reed technique. Furthermore, the posterior leaflet was slid to augment the septal leaflet. We managed to regulate the TR by enlarging the septal leaflet, thus increasing the coaptation zone. We believe that this technique will be useful for TR with annulus dilatation in HLHS.