Abstract: Being a new detection technique, ground penetrating radar(GPR) was widely used in civil pipeline detecting process. The theory and technique of GPR were introduced. Based on the application of RAMAC type GPR in pipeline detection at Shanghai, it showed the effectiveness of RAMAC for the location and size detection of non-metallic underground pipe(such as water supply pipes and gas pipes), integrated pipe and near-trench spacing pipes with fast, efficient, and nondestructive testing advantages. Compared to the traditional GPR, RAMAC GPR was superior on operation convenience, fast data processing and high image resolution. If RAMAC GPR was used combined with the pipeline detector, it would be able to solve most of the civil pipeline investigation difficulties and hence was worth while promoting.