Abstract: To address the high localization error of range-free localization algorithms, this paper proposes a MDS-MAP localization algorithm based on estimated distances. First, we analyze the relation between the distance of two neighbor nodes and the intersection area of them, and get a function. The input of the function is the number of nodes within the intersection area and the number of nodes within in the communication range of a node. The output is a distance parameter which can represent the distance of neighbor nodes. We use the distances of anchor nodes and the distance parameter of neighbor nodes to calculate estimated distances between neighbor nodes. Then, we calculate the estimated positions of non-anchor nodes based on estimated distances and the MDS-MAP algorithm. Simulation results show that the localization error of the proposed algorithm is lower than the current range-free algorithms.