Communication network plays an important role in digital substation.With the process bus instead of the traditional hard connection,substation network extends from the secondary system to primal system and the network scale and its flux increases greatly,which requires most of the information transmission real-time and with reliability,so the information security becomes more important for the secure,stable,economic and superior operation of substation.This paper introduces the method of the classification of information in order to increase its punctunality in substation. In the light of the computer network structure in substation some security strategies and measures are proposed and various techniques are described such as the firewall,mobile agent,virtual private network and data encryption algorithm and analyzes its effect.