A method, device and system for authenticating gateway, node and server are provided in this invention. The node receives a message sent by a gateway, wherein the message comprises a number T3 shared by the gateway and a server, and a gateway identification. The node encrypts data with a key K1 shared by the node and the server, the data including T3, the gateway identification, and a random number T1 generated by the node, and then sends the encrypted data and a node identification to the server through the gateway. The node decrypts data encrypted by the server and forwarded by the gateway with the key, determines that the server is a valid server according to a T1-related number obtained by decryption, and establishes a security channel with the gateway according to a new key obtained through the decryption.