The Bounding Cube algorithm used in wireless sensor networks depends greatly on the known nodes. When the number of known nodes is limited, the communication range of the unknown node is only decided by the intersection range of known nodes, which will reduce the positioning precision. This paper presents an improved algorithm. After acquiring the communication range of unknown nodes, you can use it to update the communication range of the other unknown nodes. By constantly updating the range, the unknown nodes will be gradually reduced. Thus, with the limited number of known nodes, we can take advantage of the unknown nodes to reduce the estimated communication range of other unknown nodes and improve the location accuracy.