The spare items trade among college students is one of the main activities of college extracurricular life. Due to the convenience of in-person trading, high reuse rate, low price, environmental conservation, and other reasons, the spare goods trading on campus is favored by college students. The information of spare items in traditional schools is released through QQ group, which has no security guarantee, information cannot be integrated, and information within the group is easy to be ignored. In order to bring better spare items trading user experience, the platform builds the front end of the spare item information platform based on the QQ mini-program, and builds the back end of the platform based on the Flask+MySQL frame, which has fully realized all kinds of functions of second-hand trading information platform, including multi-dimensional commodity classification, commodity recommendation, message reminder, price reminder, one-click to add friends, and so on. The platform achieves the front end and the back end encryption interactions through HTTPS and RESTful API, and introduces the function of school identity authentication, which perfectly meets the various functional requirements while ensuring the security of campus spare items trade.