1, health problems: Second-hand books may bring some health problems, such as mites, dust and bacteria in the books, which may have an impact on children's health.

2. Quality problem: The quality of second-hand books may not be as good as that of new books, such as broken pages and blurred handwriting. These problems may affect children's reading experience and even affect their reading interest.

3. Readability: Second-hand books are not necessarily suitable for children to read, for example, the content is outdated and difficult. These problems may affect children's reading effect and even make them lose interest in reading.