Abstract: A relative self-positioning method for small-scale underwater acoustic network nodes without precise synchronization is proposed.Aiming at small-scale underwater acoustic network with few quantity of nodes,the distances between two nodes are ranged by underwater communication without precise synchronization.The position of each node is corrected according to the distances of triangles made up of adjacent nodes.In simulation of several typical topologies,when the ranging error is less than 10 m,the initial positioning error is reduced by more than 40%.Relative selfpositioning during the self-organization of underwater acoustic network can avoid the traditional secondary positioning process,save energy consumption and time of positioning,improve the positioning accuracy to a certain extent.