Abstract: The transmission security of important agricultural information on networks was discussed. A public key cryptosystem (PKC) can be mplemented using an elliptic curve (EC) on a finite field. The EC-based public key cryptosystem needs shorter keys when keeping the same security. Information hiding stores a secret message into another cover message, so the secret message will not be seen. High efficient information hiding can be implemented using 24bit BMP images. Through combing encryption with information hiding, a scheme for improving the security of transmitted important agricultural information was proposed. The important agricultural information was firstly encrypted using an EC-based public key cryptosystem, and then its ciphertext was hidden into a 24bit bitmap file to be transmitted on Internet. The scheme is a double secure protection way for important agricultural information transmitted on networks, therefore it guarantees the transmission security of important agricultural information on networks.