Abstract: On the basis of the optimisation design theory and practice of classical terrestrical control network oberserved with distance, direction or azimuth, a simulative method for optimisation design and calculation of GPS horizontal network is proposed with calculating procedure and steps in detail. This paper also points out what must be paid attention to GPS network design: the accuracy of network points depends upon the datum; the GPS base linevector can be from some hundred meters to more than 20 km.