In recent years, with the construction of new power systems, the traditionally relatively closed power grid needs to be opened in an orderly way. The new power system forces more and more heterogeneous mass terminals to be exposed and deployed in the external network, and the power information system interacts frequently with the external system, increasing the attack surface, easy to be external mapping network key information, and increasing pressure of unknown attack. In order to realize the effective protection of network key information, reduce the risk of illegal detection and network attack, and provide technical support for the security protection of new power system. The first part of this paper is to solve the new attack threats faced by the power information system infrastructure by studying the network attack prevention and monitoring technology based on active intelligent defense. The second is to solve the increasingly serious problem of network scanning feature recognition by studying the defense strategies based on feature hiding and information confusion. In this way, the network security protection ability can be improved, and the construction of new power system can be strongly supported.