Abstract: In order to enhance the officiency of road shape detection, DGPS / DR combination location technology and computer technique are utilized to gain road points coordinate and compute the line-shape parameters by the coordinate in real time. Some key problems are studied, which include the data processing of combination location system, the deduction of the theoretical formulas of computing highway curve parameters and its program implement result. It is testified by the detection data of some sectins of Shanxi Taijiu freeway in China that the error of circle radius is about 0.696 m.