Encryption and decryption data transmission method and device based on 5GC Internet of Things private network

The invention relates to the technical field of communication, and provides an encryption and decryption data transmission method and device based on a 5GC Internet of Things private network. The method comprises the following steps: a first user sends an encrypted message carrying an SIM card number, manufacturer authentication information and encrypted transmission data to a network, and the destination address of the encrypted message is a preset destination address; the UDM node decrypts the manufacturer authentication information in the encrypted message by using each K4 key stored in the UDM node, and establishes a relationship between a first address of the successfully decrypted K4 key and the card number of the first SIM card; and each UPF node sets the first address as a destination address of the encrypted message so as to transmit the encrypted message to a server of a manufacturer. According to the invention, the preset destination address is used as the false destination address of the message,