Adolescent girls undergo a transformative period of both physical and emotional changes. Menarche, the first onset of the menstrual cycle, is one of the physical changes, and this could be a challenging time for the girls. For many, menarche remains a difficult experience in both developed and developing countries due to limited understanding and awareness of this process. An inadequate explanation of menarche by the family or society can lead to positive emotions during this transition. Unfortunately, limited availability of puberty education persists, particularly in low- and middle-income countries, including China. In this cross-sectional paper-based survey study with a moderate sample size, we evaluated Chinese adolescent girls' knowledge and emotional responses to menarche. The study included 2,032 teenage girls aged 10 to 17 from primary and middle schools in Shanghai and Yunnan Province, China. The mean age at menarche was 12.7 years. 36 % of the participants did not receive any information about menarche before their first menstrual cycle. Mothers, rather than schools, were the primary source of knowledge about menarche and also the main individuals girls sought advice from. The school provided limited knowledge on menstruation, leaving many girls without the necessary knowledge. Additionally, 57 % of adolescent girls reported experiencing varying degrees of negative emotions regarding menarche. Given that the average age of pubertal onset is now below ten years, our paper-based survey highlights the growing importance of puberty education, including stating earlier that it needs to be a high priority in managing adolescent girls' health, at least at the community level in low- and middle-income countries.