The workspace Measuring and Positioning System(wMPS) is an indoor large-scale positioning system based on rotating laser planes. It can provide 3D coordinates with metrological accuracy, applicable in manufacturing and assembly. As a distributed positioning system, the wMPS also has problem with assigning weights to different measuring nodes. Considering the complexity of the error sources in the positioning process, a method which uses statistics to assign different weights to different nodes was proposed according to different measuring areas. To validate the efficacy, the experimental results are presented to show that the proposed approach can improve the measurement accuracy significantly.