This application provides a key configuration method. A session management network element receives a request for end-to-end communication and obtains a security policy, where the security policy is determined based on at least one of: a user security requirement that is of the user equipment and that is preconfigured on a home subscriber server, a service security requirement from the user equipment, a security capability requirement supported by the user equipment, a security capability requirement from a carrier network, and a security requirement of a device on the other end of the end-to-end communication. The session management network element obtains a protection key used for protecting the end-to-end communication. The session management network element sends the security policy to the devices on two ends of the end-to-end communication.