Received signal strength indication (RSSI) is one of the primary location techniques, which has been popularly used in ZigBee wireless sensor network. In this paper, the authors suggest to use RSSI-based technique to design a three dimensions location and finally realize valuables guardian system within an intelligent environment supplied with indoor ZigBee network. Several mobile nodes can be freely attached to the valuables and the movement of the nodes will be monitored by the system in period. Hierarchical alarm mechanism could be issued when some abnormal movements have been identified according to some pre-defined rules. The misstatement rate is low in the experiment.