Beacon nodes are playing an important role in wireless sensor networks（WSNs） localization

which are used as the reference nodes to calculate the target position.But

the unnoticed changes of locations of some beacons may occur because of various reasons in the actual environment of WSNs applications.So

the moved beacons may become unreliable nodes and at this time if we depend on the moved beacon nodes to locate the unknown node may affect the localization precision

and even lost the use value.A scheme of beacon movement detection based on the available beacon（BAB—BMD） is proposed

aiming at the problem of beacon node movement.This algorithm detects all the beacon nodes and calculates reliability for each beacon which is received by the unknown nodes before the localization.Then select the high reliability of beacon nodes as the reference nodes in the first place for localization which is beacon optimal selection based on the available beacon（BAB—BOS）.Experimental results show that BAB— BMD has good detection for beacon movement.At the same time

BAB—BOS also has a better positioning accuracy compared with no detection of beacon movement and discard the moved beacon.