Hypospadias is a common congenital malformation in pediatric urology, due to the incomplete development of the anterior urethra in the embryonic period so that the opening of the urethra can not reach the normal position, and in recent years there is a gradual increase in the trend of the urethral orifice ectopic, penile downward curvature, abnormal distribution of the foreskin. In the process of diagnosis and treatment, friends are very concerned about the cause of the disease, so the details are as follows: I. Etiology and pathogenesis Normal external genitalia in the 12th week of embryonic development is completed. Any reason during the embryonic period leads to incomplete fusion of the urethral groove that is the formation of urethral hypospadias. 1, genetic factors: urethral hypospadias has obvious family tendency, this disease is polygenic inheritance. 2.Hormonal abnormalities: chorionic gonadotropin (HCG) stimulates testicular mesenchymal cells to peak in the 12th week of pregnancy. Testosterone is converted to dihydrotestosterone (DTH) by 5α reductase. The development of external genitalia is regulated by dihydrotestosterone. Any cause of insufficient or delayed production of testosterone or an abnormality in the conversion of testosterone to dihydrotestosterone can lead to reproductive malformations. Hormonal abnormalities may exist in the following parts of the embryonic period, affecting urethral development: ① insufficient HCG production; ② fetal testes are insensitive to HCG; ③ insufficient production of testosterone or delayed peak later than 12 weeks; ④ 5α reductase deficiency, abnormal conversion of testosterone; ⑤ abnormalities of the mother’s pre-pregnancy hormone intake. 3.Abnormal androgen receptor: androgen receptor gene mutation is one of the causes of hypospadias. 4.Epidermal growth factor and its receptor abnormalities. Second, the clinical manifestations of typical urethral hypospadias has three characteristics: ectopic urethral opening, penile recurvature, abnormal distribution of foreskin. 1, ectopic urethral opening: the urethral opening can be ectopic opening from the normal urethral opening proximal to the perineal urethra in any part. The urethral opening is mildly narrowed, with a shallow mucous membrane-like groove at its distal end, partially covered by a film. The child often urinates in the squatting position, and the urethral opening is more pronounced the more proximal it is to the body of the penis. According to the location of the urethral opening urethral hypospadias is divided into five types: (1) the head of the penis, the coronal groove type; (2) the penis body type; (3) the penis scrotum type; (4) scrotum type; (5) perineum type. 2, penile hypospadias: hypospadias mostly exists in the penis to the ventral side of the bend, the cause is mainly the urethral plate fibrous tissue hyperplasia distal to the urethral orifice, the lack of subcutaneous tissue in all layers of the ventral side of the body of the penis, and asymmetric dorsal and ventral sides of the corpus cavernosum of the penis. According to the angle between the head of the penis and the longitudinal axis of the penile body, penile recumbency is divided into: (1) mild: less than 15 °; (2) moderate: 15 ° ~ 35 °; (3) severe: more than 35 °. Abnormal distribution of foreskin: Hypospadias is characterized by cap-like accumulation of foreskin on the dorsal side of the penis, V-shaped defect of the ventral foreskin, and absence of foreskin tie. Combined deformities: the most common combined deformities are inguinal hernia and cryptorchidism; severe hypospadias sometimes combined with prostate capsule, sometimes resulting in infection and stones; accompanied by upper urinary tract deformities; some cases combined with penile scrotum transposition, penile torsion, small penis, duplicate urethra and so on. Third, the treatment of urethral hypospadias has many treatment methods, but no matter what method should reach the currently recognized cure standard: (1) penile recurvature is completely corrected; (2) urethral orifice is located in the positive position of the head of the penis; (3) penile appearance is satisfactory, close to normal, able to stand up to urinate, and can have a normal sex life after adulthood. Surgical treatment includes staged plasty and one-stage urethroplasty. Stage-forming surgery refers to the urethroplasty performed 6 months to 1 year after the correction of penile recurvature in one stage. One-stage urethroplasty includes correction of penile recurvature, urethroplasty, urethral orifice and penile head shaping, ventral penile trauma coverage and scrotal shaping, etc. It requires a high level of surgical operation experience and skill, to be completed by a professional and senior surgeon, and to be accompanied by a good post-operative care.