Objective To summarize the characteristics of children diagnosed with secondary subaortic stenosis after the surgical closure for ventricular septal defect and explore its potential mechanism. Methods We retrospectively collected patients aged from 0 to 18 years, who underwent ventricular septal defect closure and developed secondary subaortic stenosis, and subsequently received surgical repair from 2008 to 2019 in Fuwai Hospital. Their surgical details, morphological features of the subaortic stenosis, and the follow-up information were analyzed. Results Six patients, including 2 females and 4 males, underwent the primary ventricular septal defect closure at the median age of 9 months (ranging from 1 month to 3 years). After the first surgery, patients were diagnosed with secondary subaortic stenosis after 2.9 years (ranging from 1 to 137 months). Among them, 2 patients underwent the second surgery immediately after diagnosis, and the other 4 patients waited 1.2 years (ranging from 6 to 45 months) for the second surgery. The most common type of the secondary subaortic stenosis after ventricular septal defect closure was discrete membrane, which located underneath the aortic valve and circles as a ring. In some patients, subaortic membrane grew along with the ventricular septal defect closure patch. During the median follow-up of 8.1 years (ranging from 7.3 to 8.9 years) after the sencond surgery, all patients recovered well without any recurrence of left ventricular outflow tract obstruction. Conclusion Regular and persistent follow-up after ventricular septal defect closure combining with or without other cardiac malformation is the best way to diagnose left ventricular outflow tract obstruction in an early stage and stop the progression of aortic valve regurgitation.