In order to solve the problem that there is large errors in DV-Hop algorithm in network topology environments, a modified RSSI-based WSN localization algorithm RMDV-Hop (RSSI Modify DV-Hop)is presented in this paper. The algorithm limits the maximum number of hops and uses RSSI value to modify its hop value when hop of an anchor node is 1. The first N anchor nodes with greater RSSI value is chosen as reference anchor nodes and per hop distance error of the reference anchor nodes are used to weight average hop distance of the unknown node. Finally，a total least squares method is used to calculate the coordinates of the position of the unknown node to achieve overall improvement of RMDV-Hop localization algorithm and improve the positioning accuracy. The simulation results show that the positioning accuracy and stability of the improved algorithm has been significantly improved than those of the original algorithm.