First, the initial connection isolation method ICS is established to separate false connections generated by malicious network behaviors from normal established connections, and form a controllable initial connection table. A strategy combining extended RSVP protocol and DiffServ model is designed to ensure the realization of QoS in large campus network. The simulation test results show that the application of this model can effectively improve the QoS of large-scale campus networks, and the problems that need to be paid attention to when running the parallel operation of the database management system correctly in the network environment. Especially to prevent data corruption and loss when developing multi-user systems.