Aiming at the disadvantages of current handoff mechanisms in micro-mobility protocols, active handoff mechanism is proposed. This mechanism takes advantage of mobility prediction technique to predict the next cell a mobile host will handoff to and the handoff time before the handoff really happens and establish the new path for the mobile host in advance. To guarantee the implementation of active handoff mechanism, a mobility prediction algorithm is proposed which is suitable for active handoff mechanism and easy to implement. Meanwhile the methods to avoid packet loss and packet duplication in active handoff procedure are proposed. The performance of active handoff mechanism is evaluated through theoretical analysis and system simulation. The result shows that active handoff mechanism obtains considerable performance improvement with less cost.