1. Donation: Donate the old books of the Public Security University to the school library or other relevant institutions, such as the public library and the school book donation program. Donation can benefit more people and reduce waste.

2. Transfer: If the book still has high use value, it can be transferred through second-hand bookstores and online book trading platforms. This will allow others to buy and use these books.

3. Recycle: If books are badly worn or can't be used any more, you can recycle them. Recycling can be used to recycle paper and reduce the waste of resources.

4. Retention: For special old books, such as precious ancient books or classic teaching materials of specific disciplines, you can choose to keep them in the school library or special collection institutions for academic research or exhibition.