As wide applications of wireless sensor networks, privacy concerns have emerged as the main obstacle to success. When wireless sensor networks are used to battlefield, the privacy about sink-locations become a crux issue. If sink location will be exposed to adversary, the consequence is inconceivable. Random data collection scheme has a problem that message latencies become larger higher for protecting mobile-sink-locationprivacy .In this paper, BDRW (Bidirectional Random Walk) is proposed to preserve mobile-sink-location privacy. In BDRW, data are forwarded by directional random walk and stored at pass nodes in the network, the sink move in directional random walk to collect data from the local nodes occasionally, which prevents the attackers from predicting their locations and movements. Compared to random data collection scheme, BDRW has smaller message latencies, while providing satisfactory mobile-sink-location privacy.
