Selling old books can be done in the following ways: 1. Post information on second-hand bookstores or online second-hand trading platforms: These platforms can post information such as Taobao, Craigslist, Facebook Marketplace, and so on. 2. Bring the old books to the local secondhand book market or bookstall to sell them on the spot: These markets usually have many sellers and buyers who can directly view and trade them on the spot. 3. Contact the publishing house or ask if there is a plan to collect old books: Some publishing houses may take the initiative to ask and participate. 4. Set up vending machines in second-hand bookstores or online second-hand trading platforms: Set up vending machines or regular reminders to sell old books to save time and energy. No matter which method was used, the quality of the old book must be ensured and the packaging must be carefully checked to ensure the safety of the book.