Embodiments of the present invention disclose a method, apparatus and system for obtaining key information during fast channel switching. A fast channel switching request sent by a terminal is received; at least one data unit bearing key information is generated according to the fast channel switching request; a fast channel switching response message is sent to the terminal, where the response message carries an identifier of a first data unit bearing the key information and the number of data units bearing the key information; and the at least one data unit bearing the key information is sent to the terminal. When the key information is lost, the key information is retransmitted without a need to perform status maintenance, which improves scalability of fast channel switching.