This paper provides a state-of-the-art survey of location privacy-preserving techniques in WSNs. First, the network model, the attack model and the performance evaluation model are reviewed. Then, existing work is classified into four types, including path camouflage, entrapment attracting, network anonymity and communication control. Further, the key mechanisms of typical location privacy-preserving protocols are elaborated. Performance analysis and comparison show that all these four strategies affect communication and energy efficiency in some degree. In addition, the path camouflage strategy mainly aims at hop-by-hop trace attack, the network anonymity strategy aims at ID analysis attack, while the entrapment attraction and communication control strategies are capable of resisting multiple types of attacks. Finally, suggestions for future research are provided.