A method for deleting session information of a User Equipment UE or an IP Internet Protocol Connectivity Access Network IP-CAN session of the UE in a visited Diameter Routing Agent DRA and a home DRA, adapted to an Evolved Packet System under a roaming scene, wherein the method comprises: sending a request message for deleting a Diameter session belonging to the IP-CAN session or belonging to the UE to the visited DRA and a visited Policy and Charging Rules Function PCRF by a policy and charging control client, wherein the Diameter session is a session between the policy and charging control client and the visited PCRF; marking the Diameter session in the visited DRA as terminated by the visited DRA after the visited DRA receives the request message; and sending a message to the home DRA by the visited PCRF, after the visited PCRF receives the request message, to request to delete information of the Diameter session, and marking the Diameter session in the home DRA as terminate by the home DRA; after the visited DRA marks the Diameter session as terminated, when all Diameter sessions belonging to the IP-CAN session or all Diameter sessions belonging to the UE in the visited DRA are deleted, the visited DRA deletes all the session information of the IP-CAN session or of the UE; or after the home DRA marks the Diameter session as terminated when all Diameter sessions belonging to the IP-CAN session or all Diameter sessions belonging to the UE in the home DRA are deleted, the home DRA deletes all the session information of the IP-CAN session or of the UE; wherein the step of the visited DRA marking the Diameter session as terminated refers to making a mark in the visited DRA to indicate that the Diameter session has been released; the step of the home DRA refers to making a mark in the home DRA to indicate that the Diameter session has been released. sending a request message for deleting a Diameter session belonging to the IP-CAN session or belonging to the UE to the visited DRA and a visited Policy and Charging Rules Function PCRF by a policy and charging control client, wherein the Diameter session is a session between the policy and charging control client and the visited PCRF; marking the Diameter session in the visited DRA as terminated by the visited DRA after the visited DRA receives the request message; and sending a message to the home DRA by the visited PCRF, after the visited PCRF receives the request message, to request to delete information of the Diameter session, and marking the Diameter session in the home DRA as terminate by the home DRA; after the visited DRA marks the Diameter session as terminated, when all Diameter sessions belonging to the IP-CAN session or all Diameter sessions belonging to the UE in the visited DRA are deleted, the visited DRA deletes all the session information of the IP-CAN session or of the UE; or after the home DRA marks the Diameter session as terminated when all Diameter sessions belonging to the IP-CAN session or all Diameter sessions belonging to the UE in the home DRA are deleted, the home DRA deletes all the session information of the IP-CAN session or of the UE; wherein the step of the visited DRA marking the Diameter session as terminated refers to making a mark in the visited DRA to indicate that the Diameter session has been released; the step of the home DRA refers to making a mark in the home DRA to indicate that the Diameter session has been released.