Objective To investigate the therapeutic effect of supraglottoplasty (SGP) on severe laryngomalacia (LM) in newborns requiring respiratory support and high-risk factors leading to SGP failure. Methods Twenty-three newborns with severe LM requiring respiratory support, admitted to the Neonatology Department of Hunan Children’s Hospital from January 2016 to December 2020, were selected. According to the treatment effect, they were divided into successful operation group (n=16) and failed operation group (n=7). The long-term prognosis of the successful operation group was followed up, and the risk factors of the failed operation group were investigated. Results A total of 23 operations were performed, with a success rate of 69.57%(16/23). Preoperatively, invasive mechanical ventilation was required in 22 cases (95.65%) and non-invasive ventilation was required in 1 case (4.35%). In the successful operation group, dyspnea disappeared within 12 months after birth, feeding difficulties resolved by 18 months, all children were free of recurrent respiratory infections within 24 months after birth, and laryngeal stridor symptoms disappeared by 36 months after birth. In the failed operation group, the mean age of mothers was(31.71±5.99) years, 71.40% of patients with asphyxia, 57.14% with heart disease, and 28.57% with genetic related diseases. Compared with the successful operation group, the mothers in the failed operation group were older and the patients had more concomitant diseases, and these differences were statistically significant (P<0.05). Conclusions SGP has a relatively high success rate for severe LM in newborns. Surgical failure is more common in cases with older mothers, concomitant perinatal asphyxia, congenital heart disease, genetic related diseases and other factors.