The identity authentication between the existing satellite network nodes mostly relies on a certificate authority，i.e.，an authorized authentication server，which is prone to central bottlenecks and single points of failure.Moreover，the authenticated nodes are likely to suffer malicious attacks in the future，leading to the tampering of key configuration files and thus leaving firmware backdoors.In this paper，the blockchain and smart contracts are used to build a secure communication framework for satellite network systems.Through the blockchain，an identical tamper-proof and traceable distributed ledger is provided for all nodes in the network，so that identity authentication no longer requires a trusted intermediary.The distributed identity authentication can be realized directly through point-to-point，and the integrity of the key data of nodes can be regularly verified through smart contracts to strengthen the system security protection.Finally，a prototype is implemented on an open source blockchain platform，and verifies the secure communication mechanism.