Remote examination system (ES) has become possible and has achieved certain results. There are many problems in school management and information exchange between teachers and students. We need to develop a new efficient, convenient, safe and reliable online ES. In this paper, BP network algorithm is studied. This paper mainly uses the experimental method and the comparative method to test the ability of the online ES. The experimental results show that the packet loss rate of the system designed in this paper is smaller than 0.1 within the controllable number of people. However, when the number of people exceeds 600, the packet loss rate increases. Therefore, the system designed in this paper is feasible within a certain range.