This thesis designs a network teaching and leaning Platform based on .NET framework and web technology. The Platform realizes easy communication and interaction between teachers and students under the network teaching and learning environment. In this environment, teachers and students work in collaboration, which helps to promote students' self-learning abilities and collaborative leaning abilities. Based on requirements analysis in network teaching, the system determines the basic functions of the network teaching and leaning platform. It builds part of software model of the system by using Software Engineering methods. It also designs a system interface, database and some functions of teaching, learning, assignment, examination, course answering and so on, and realizes the online examination system, as well as the Forum and Q & A subsystem.