The present invention discloses a data processing method for network layer in a home network system (1) based on a living network control protocol. The data processing method for network layer based on a protocol, that is composed of at least a physical layer, a data link layer, a network and an application layer, includes the steps of: receiving a message sending primitive (MsgSend) in application layer protocol data unit (APDU) frp, the application layer; according to the message sending primitive (MsgSend), generating a communication cycle description; according to the message sending primitive (MsgSend) and/or the communication cycle description, generating a packet sending primitive (PktSend) in network layer protocol data unit (NPDU); and transmitting the packet sending primitive (PktSend) to the data link layer.