Abstract: The structure of shale gas pipelines is complex, with surface structures such as curved surfaces, elbows, tees, crosses, etc., and the wall thickness variation area caused by erosion and corrosion is large and irregular. This makes it difficult for conventional single-point ultrasonic monitoring methods to achieve full-coverage monitoring of shale gas pipeline wall thickness, which may result in undetected dangerous points of wall thickness change. Therefore, aiming at the difficulties in online monitoring of large-area, high-precision and high-temperature (100 ℃) wall thickness of shale gas pipelines, a wall thickness monitoring method based on flexible array piezoelectric sensor was proposed. A high temperature resistant multi-channel flexible array piezoelectric sensing system was designed and fabricated, and high temperature, vibration, precision and long-term monitoring tests were carried out. The test results show that the new monitoring method has high accuracy and stability, and can realize long-term large-area monitoring of the wall thickness of shale gas pipelines, which provides conference for the safe operation and maintenance of shale gas pipelines.