SOUTH GPS9800 is applied in landform mapping controlling net to conduct datas in Changqing economic developing area of Jinan city. By applying GPS technology, three dimensional coordinates and geodetic altitude are measured accurately. Through fourth class altitude, normal altitude of this spot is measured, then abnormal value of this spot is determined. Thus, if GPS spots can be laid as many as possible, through the already gained abnormal value of altitude, normal value of controlling spots can be determined more accurately.