In many situations, the governmental agency in charge of the underground pipes is unaware of the exact position of the pipes. The lack of efficient pipe management may potentially lead to the dangerous situation in which the underground pipes are destroyed during engineering excavation. The development of a non-destructive and efficient technique to locate underground pipes has therefore become important. The purpose of this study is to evaluate the applicability of ground penetrating radar (GPR) method in positing underground pipes by field tests on some different kinds of under-ground pipe. The reflections comes from an underground pipe is very particular diffraction pattern because the size of a pipe is normally small. The locations of underground pipes can be well delineated from the distribution of diffractions on the radar profile. The response of iron pipe is very obvious due to the strong reflection signal. Two closed iron pipes also can be distinguished from the radar profile. The sewer and drain pipes which are made of concrete also can be detected from the properties of multiple and flat reflections. It is difficult to detect the PVC pipe, because the reflected signals coming from a PVC pipe are very weak. The reflections coming from a PVC pipe can be enhanced if the background signal can be removed through measurement. The background removal technique can be added to detect PVC pipe.