This article introduces a measuring method based on Unified Spatial Metrology Network (USMN).In large-scale engineering measurement, one instrument in one position cannot fulfill the task.Moving instrument to different positions or more than one instrument is needed. Instead of accumulating error by Best-fit in traditional way, the USMN can reduce the cumulative error by redistributing the weights of fitting elements. Therefore it increases the accuracy of multi-station measurement method? and provides an effective means in large scale engineering measurement. By comparing and observing the close degree of endˉtoˉend and changes in radial direction of two methods, the USMN has been found closer to real situation than the traditional one.