Objects: Indentifying the ratios and characteristics of hearing loss of preschool children aged 2 - 5 at the public nursery schools of internal Hanoi. Methods: A cross-sectional study using Otoacoustic Emissions (OAE) for hearing loss screening was conducted in pre-primary schools with 2-5 years old kids at the public nursery schools of internal Hanoi. Children were classified as "Refer" will be referred and tested Auditory Brainstem Response (ABR) or single syllable to confirm hearing loss and assess its characteristics at National Hospital of Pediatrics. Results: 4.4 percent of hearing loss was found among 7191 pre-school children who participated in the hearing loss screening. The ratio of hearing loss in boys and girls were 4.7 percent, and 4.0 percent, respectively. Bilateral hearing loss was highest prevalence rate among hearing loss children with 70,1 percent. Of the hearing loss total, mild hearing loss was the most common hearing loss among the prevalent group, accounting for 45.9 percent, profoundly to severe hearing loss got the high rate of 12,6 percent. Conclusions: The prevalence of hearing loss among preschool children aged 2-5 years old in inner of Hanoi was 4.4 percent. Bilateral hearing loss and mild hearing loss were the two most popular characteristics of the hearing loss children, 70.1 percent and 45.9 percent, respectively.