Abstract: To assess the basic conditions of pipeline and the trends of various defects, the pipeline body should be detected as early as possible. The detection result, which is regarded as the basis of pipeline physical conditions and also the criterion for future assessment of defect changes, is known as the baseline. Currently, the requirements for higher safety and lower operating costs of pipeline make the scientific decision more and more important to pipeline defect repair and detection. The detection of baseline conditions of pipeline becomes the crucial part of pipeline assessment management. Generally, baseline detection refers to the comprehensive detection of the pipeline body, including internal detection and external detection. This paper introduces the concept and process of baseline detection, and compares engineering standard and applicability evaluation standard. Moreover, this paper presents the challenges for the baseline detection, the different recognitions of various defects in two stages (project management and operation management), and finally the suggestions on the baseline detection. It turns out that the baseline detection is an important guarantee of safe pipeline operation.