Objective: Report a novel technique of flexible endoscopy (FE) with noninvasive ventilation (NIV) and sustained pharyngeal inflation (FE-NIV-SPI) in assessing aeroesophageal tracts (AET) to facilitate early detect laryngeal clefts (LC). Methods: Medical charts and FE videos of the children who were diagnosed as LC in a tertiary care hospital between 2000 and 2020 were retrospectively reviewed and analyzed. FE-NIV-SPI technique was applied for all the reviewed children. Results: Of all the FE videos reviewed, twelve infants with laryngeal clefts were collected. This equates to a prevalence of 0.28% in all the children underwent FE at our institution. Their mean age was 5.0 ± 4.9 month-old and the mean body weight was 4.7 ± 2.3 kg. Nine (75%) infants were referred in without LC diagnosis, which was missed by 11 prior bronchoscopy and 5 computer tomography exams. With FE-NIV-SPI, the pharyngolaryngeal space could be pneumatically expanded and allowed detailed assessment. All LC types and coexisted AET lesions were visualized at the first FE-NIV-SPI examination with a mean time of 4.2 ± 0.9 minutes. They were eight type I, two type II and one type III. Ten (83.3%) infants coexisted airway malacia. Conclusion: Routinely using the FE-NIV-SPI technique can help detect the LC defect and associated AET lesions at the first assessment.