With the popularity of the Internet, e-commerce business has developed more and more rapidly. People can place orders and pay for all kinds of goods on the website anytime, anywhere. At the same time, the second-hand trading market has gradually entered people's field of vision as an emerging e-commerce category. Modern consumerism has increased tremendously in line with economic development. While this has greatly increased the dynamism of the market, it has also led to a huge accumulation of unused items that consumers do not use at the moment or that are obsolete for them. The second-hand market has emerged as a means of disposing of these unused items. At present, a large number of companies have created second-hand commodity trading platforms. In China, well-known trading platforms include xianyu, owned by Alibaba, and in the UK, ShpockShpock is already the most popular platform of the moment. However, these platforms have some problems, such as frequent fraud, complex user population, and poor convenience. The purpose of this project is to analyse the problems existing in the existing second-hand trading platforms, propose improvement measures and develop a second-hand trading platform for Cardiff University students that can solve such problems. To allow users to enjoy the convenience brought by the second-hand trading platform while ensuring security, and to bring users the best trading experience. Based on the above objectives, the project has conducted a lot of research into the technical solutions, and after detailed research chose to use the classic development framework of spring boot & html, and completed the development of the complete project based on prototype drawings. The project also explored the security issues and came up with constructive solutions, including functional and non-functional means such as banning online payments and limiting the identity of registered users. As a conclusion, this project has built a student-oriented second-hand trading platform that guarantees a user-friendly second-hand trading experience and provides strong security.