Objective:To explore the characteristics of abnormal chromosome karyotype of common external genital malformations in male children.Methods:A retrospective analysis of the clinical data of 2 408 children was made in outpatient or inpatient from January 2012 to December 2017. The mean age was (38±7) months. There were 1115 cases of hypospadias, 189 cases of cryptorchidism, 304 cases of micropenis, 681 cases of concealed penis and 119 cases of disorders of sex development. All children were tested for chromosome 550 band in peripheral blood, and the results of chromosome karyotype were analyzed.Results:A total of 131 cases of abnormal chromosome karyotypes were detected, with a detection rate of 5.4%, including 46 cases of chromosome number abnormalities, 85 cases of structural abnormalities, 64 cases of sex chromosome abnormalities and 67 cases of autosomal abnormalities. The karyotype of chromosome was 46, XY, inv (9) (p12q13) in 28 cases accounting for 21.4%. It was followed by 47, XXY, with 16 cases, accounting for 12.2%. The detection rate of chromosomal abnormalities in children with disorders of sex development was 12.6%(15 cases), hypospadias was 5.5%(61 cases), cryptorchidism was 5.3%(10 cases), micropenis was 4.9%(15 cases), and concealed penis was 4.4%(30 cases).Conclusions:Chromosomal abnormalities are not uncommon in male children with external genital malformations. Chromosome structural abnormalities are more common than quantitative abnormalities, and sex chromosome abnormalities account for a comparable proportion to autosomal abnormalities.