Due to the lack of drawings and familiarity with the traffic, the efficiency of the reconnaissance for line projects was low. Through ACAD2KML, a plug-in of AutoCAD, the AutoCAD drawings could be made into a KML file, which can be imported into Google Earth to read the terrain and profile along the project. Intuitive understanding will be obtained for the route selection and route adjustment for  the liner project. At the same time, through connecting handheld GPS with Personal Computer installed with Google Earth by data line, GPS navigation could be associated with Google Earth map to provide convenience for field reconnaissance and to improve work efficiency.