Background: The growth of adolescents is affected by economic development and education levels. We investigated the first spermatorrhea age of adolescents in urban area and in rural area of Jiangsu province, China. Methods: The data were obtained through anonymous questionnaire by using cross-sectional methods. From May 2016 to March 2017 in Jiangsu province, China, a total of 2131 Han nationality students were enrolled in cluster. The survey was contained date of birth, age, grade, age of first spermatorrhea and how long ago of the first spermatorrhea, all data were analyzed by Prism 8.0. Results: The questionnaire accounted for response was 97.3%, and the effective rate was 96.3%. The mean age of first spermatorrhea was (13.7 ± 1.5) years old, which included 13.6 ± 1.4 years in urban and 13.9 ± 1.5 years in rural. The first spermatorrhea occurred in the fifth and sixth grade primary school, and 1, 2, 3 grades of junior high school were 3.5%, 13%, 27.4%, 28.5% and 15.1%, respectively. There was 62.3% of first spermatorrhea occurred in summer. The rate of spermatorrhea with natural occurrence accounted for 95.1%, and with active accounted for 4.9%. Conclusions: Compared with rural area, the age of the first spermatorrhea of males in urban area is significant earlier. The adolescent’s first spermatozoa were mostly occurred in summer. The relevant physical and reproductive education should be started from the third grade of primary school. The reproductive health education should be carried out when the youth are 7 years old.