A method and a device for negotiating encryption information are provided. In one embodiment, the method for negotiating encryption information includes: obtaining information about encryption capabilities of a first device and information about encryption capabilities of a second device; determining encryption information applicable to the first device and the second device according to the information about encryption capabilities of the first device and the information about encryption capabilities of the second device; and sending the encryption information to the first device and the second device, wherein the encryption information serves as a basis for encrypting and/or decrypting data streams between the first device and the second device. Embodiments of the present invention ensure security of data streams transmitted between a Telephony Client (TC) and a Telephony Server (TS).