Abstract: Objective：To analyze the distribution characteristics of inpatients with rare diseases in Henan Children's Hospital, and provide scientific basis for the epidemiological study of rare diseases in children.Methods：The medical records of 1 104 rare disease patients admitted to Henan Children's Hospital from 2015 to 2019 were selected for descriptive epidemiological research and analysis.Results：The average age of patients with rare diseases was 30.87 months, and the average age was in the age range of 28.97 to 32.77 months, and the age distribution showed an increasing trend from 2015 to 2019. The types of common rare diseases in children were different in each period. The main types of rare diseases in infants, early childhood, and preschool children were methylmalonic acidemia and congenital adrenal hyperplasia, while the main rare diseases in school age children were congenital adrenal hyperplasia，and hepatolenticular degeneration. The top three rare disease types were methylmalonic acidemia, congenital adrenal hyperplasia, and hyperammonemia, which accounted for 31.7%(350/1 104), 21.7%(240/1 104) and 7.4%(82/1 104), respectively in rare disease patients. Among different types of rare diseases, the ratio of men to women was quite different. The top five rare diseases with the highest ratio of men to women were in turn as follows: adrenal leukodystrophy, glutaric acidemia, phenylketonuria, Kalman syndrome, and biotin-dependent hydroxylase deficiency. The top five rare diseases with the lowest male to female ratio were in turn as follows: multiple fibrous dysplasia with precocious puberty syndrome, Wadenberg syndrome, congenital hyperinsulinemia, type II glycogen storage disease, and Niemann-Pick's disease.Conclusion：From 2015 to 2019, the age distribution of rare diseases in Henan Children's Hospital showed an increasing trend year by year, and themain types of rare diseases in children were also different in different age groups. The ratio of men to women with different types of rare diseases is quite different.

Key words: Rare disease, Distribution, Descriptive research