Abstract: A method and a system of synchronizing an unread message of instant communication are disclosed. The method includes: obtaining information of an unread message in each dialogue associated with an instant messaging account from a server when the account is logged in via a current terminal; and displaying the information of the unread message in the current terminal, wherein the unread message is a message with time information that is larger than a first time stamp in each dialogue, the first time stamp being time information of a most recently read message in each dialogue submitted by the instant messaging account, and the first time stamp corresponding to each dialogue of the instant messaging account being stored in the server.