Abstract: With the development of cloud computing,the problem of huge energy consumption has become more and more critical．State management has always been an effective way of saving energy．State management of servers can also bring an impressive amount of energy saving．A strategy based on state management was proposed to optimize energy consumption of servers in data centers,which can guarantee the performance and bring down the energy consumption at the same time．Petri nets and states analysis were used to analyze the strategy．An instance analysis and some experiments were done to show the validity and superiority of the strategy.

Key words: State management,Energy optimization,Petri net,Queuing theory