Handoff access method and device based on random access channel

A handoff access method and device based on a random access channel is provided, and includes a source BS that sends a handoff request message to a target BS; and the target BS sends a handoff response message to the source BS. The source BS then forwards a handoff command with the content of the handoff response message to the mobile terminal, wherein a sequence number of a reserved character code allocated by the target BS to the mobile terminal and a random access sub-channel that the reserved character code is located in are contained in the handoff command message. After receiving the handoff command message, the mobile terminal selects the reserved character code and the random access sub-channel that the reserved character code is located in; and a handoff access procedure is initialized on the random access sub-channel by the target BS and the mobile terminal.