The invention relates to the communication field, in particular to a routing optimizing method and a system in agent mobile IP and an agent mobile IP client, for realizing safe routing optimization of RMIP6. The routing optimizing method comprises: MAG and correlative nodes CN undergo hometown tests through a hometown agent HA so as to obtain a hometown key creating token; the MAG and the correlative nodes undergo transfer tests so as to obtain a transfer key creating token; an agent mobile IP client obtains a key for binding management Kbm and acts the binding update of the mobile nodes and the correlative nodes CN which need routing optimization, the calculation parameters of the Kbm include the hometown key creating token and the transfer key creating token. The hometown test and the transfer text can also be completed at the agent mobile IP client.