In the planning of urban underground space, the construction and maintenance of underground pipeline is very important. To achieve this, it is essential to acquire the information of the underground pineline, and the detection of the pineline is necessary,the difficulty of which is the detection of non-metallic pineline.To non-metallic pipeline with hard material and big diameter,the drilling method has been used to detect it.Based on the drilling method, two-drill method has been studied for determinating the center and depth of non-metallic pipeline. A software package has been developed and evaluated by practical applications. Results has shown the effectiveness of the proposed method.