The invention discloses a system and a method for detecting and evaluating corrosion of a buried pipeline, and belongs to the technical field of corrosion resistance of pipelines. The system comprises on-line soil corrosion detection equipment, on-line pipeline corrosion detection equipment and a corrosion evaluation and detection system, wherein the on-line soil corrosion detection equipment is arranged in the soil around a pipeline; the on-line pipeline corrosion detection equipment is arranged on a test pile of the pipeline; and the on-line soil corrosion detection equipment and the on-line pipeline corrosion detection equipment are respectively connected with the corrosion evaluation and detection system in a wireless data communication manner. By adopting the online-detection equipment, soil and pipeline corrosion data can be acquired timely, and the corrosion evaluation and detection system comprehensively and completely analyzes the monitored data of the soil and the pipeline; and the system can completely and systematically analyze the data relevant to the corrosion of the buried pipeline and timely evaluate the corrosion situation and the residual service life of the pipeline so as to timely judge the corrosion state of the pipeline.