Researchers from various nations have become increasingly interested in breast growth and bra-wearing as female puberty-timing advances and breast development ages continue to fall. To identify the issues related to underwear education in families, this study, which has a particular focus on China, examines the current state of breast development and bra-wearing among high school girls and their mothers and the correlation between mothers and daughters. The findings revealed that, while most women and girls in China are aware that wearing a bra properly can affect their physical development and health, their awareness of breast development and bra-wearing knowledge is insufficient, and the status quo of wearing bras is not ideal. Mothers play a crucial role in educating their daughters about bra-wearing in three respects: knowledge and understanding, present circumstances and behaviours and interest and desire to learn. However, the unsatisfactory state of educational outcomes in families on the issue of bra-wearing is often due to the mothers' insufficient knowledge and information, improper teaching techniques and a lack of communication with their daughters.