In order to improve the flexibility and availability of information transmission in the software defined packet transport network(SPTN), a centralized control software defined network(SDN) controller is introduced as the core of the SPTN under the framework of the SDN to realize the separation of control and forwarding. This paper studies the cluster deployment in SPTN by using the Raft algorithm to make multiple controllers work together to solve the reliability and scalability problems of a single controller node. The SDN controller cluster uses the ETCD database to realize the functions of Raft algorithm election, controller master/backup switching, data synchronization and persistence. The experimental results show that the Raft algorithm can be used normally in the SDN controller cluster, and its performance has been improved in terms of convenient network service opening, flexibility and reliability of network information transmission.