A handoff access method and device based on a random access channel is provided, the method includes the following steps: step a, a source BS sends a handoff request message to a target BS, requesting switching the mobile terminal it serves to the target BS; step b, the target BS sends a handoff response message to the source BS, and then the source BS forwards a handoff command with its content to the mobile terminal, wherein the handoff command message does not include reserved character codes; step c, after receiving the handoff command message, the mobile terminal determines that the handoff command message does not include the reserved character codes, and then selects a random access sub-channel; and step d, the target BS and the mobile terminal initiate a random access procedure on the random access sub-channel.