Due to high error of positioning in the uneven distribution of wireless sensor network node for the DV-Hop algorithm, an improvement for the DV-Hop algorithm is presented. The main idea of this improvement is to use the received signal strength indicator measurement technique to increase the anchor nodes; then, the concept of “region of existence possibility ” is introduced under certain constraints, especially, the area of “region of existence possibility ” is regarded as the objective function of optimization problem, which is solved by using the nonlinear conjugate gradient method to approach the position of a unknown node, to minimum the node positioning error. Simulation result shows a 5% to 10% increase in positioning accuracy under the impact of different node communication radius and anchor node ratio, which validated the improvement.