Data encryption and decryption method and device

The invention discloses a data encryption and decryption method and device, and relates to the field of network communication. The method comprises: a network device filters the IP addresses of all data of a link layer according to an IP address filtering rule downloaded from a server; the network device encrypts cleartext data needing to be transmitted in a network layer in an encryption manner according to a filtering result to transmit the cleartext data in the network layer; and the network device decrypts ciphertext data needing to be decrypted and transmitted by the network layer according to the filtering result. The data encryption and decryption method and device disclosed by the invention are used for selectively encrypting and decrypting data according to the IP address filtering rule to prevent sensitive information from being stolen and identified on the network.