目的　了解威海市中小学生女子月经初潮、男子首次遗精的年龄变化。　方法　采用随机整群抽样方法 ,抽取 2 398名城乡男女生 ,进行问卷调查。　结果　　 2 0 0 0年威海市中小学生女子半数月经初潮年龄 ,城市女生为12 .6 1岁 ,乡村女生为 12 .89岁 ;95 %分布范围 ,城市女生为 10 .0 1～ 14 .45岁 ,乡村女生为 10 .0 6～ 16 .5 2岁 ;与 10年前相比 ,城乡女生分别提前了 0 .2 5、0 .5 2岁 ;月经初潮的高峰年龄城、乡分别为 12～ 13岁、13～ 14岁。半数首次遗精年龄 ,城市男生为 13.5 0岁 ,乡村男生为 14 .6 4岁 ;95 %分布范围 ,城市男生为 10 .37～ 17.5 8岁 ,乡村男生为 12 .2 1～ 17.5 5岁。结论　性知识教育应提前到 12岁 ,加强青春期性健康教育尤为重要 Objective To understand the age-related changes of men’s primary spermatorrhea in primary and secondary school students in Weihai. Methods A random cluster sampling method was used to collect 2 398 boys and girls from urban and rural areas for questionnaire survey. Results In 2005, half of girls in primary and secondary schools in Weihai had the age of menarche, the urban girls was 12.61 years old, the rural girls was 12.89 years old, and the distribution range of 95% was 10.0-1.14 years Compared with 10 years ago, girls in urban and rural areas were 0.52.5,0.2 years ahead of schedule respectively. The peak age of menarche and urban areas were 12 ~ 13 years old, 13 to 14 years old. Half of the age of first spermatorrhea, urban boys 13.5 years old, rural boys 14.6 years old; 95% distribution, urban boys 10 .37 ~ 17.5 8 years old, rural boys 12.21 ~ 17.5 5 years old. Conclusions Sexual education should be advanced to 12 years old. It is particularly important to strengthen sexual health education in adolescence