Abstract: The phenomenon of oil stealing from long-distance oil and gas pipelines in China is increasing. Once the pipelinefails, it will bring huge safety risks to the operation of the enterprise and the personal property of the people. As the mosteffective detection method for hot-tap of pipeline, traditional magnetic flux leakage in-line inspection has disadvantages suchas high cost and long detection period. Therefore, a low-cost and rapid inspection tool for hot-tap based on the principle ofpermanent magnet disturbance has been developed. This article introduces the basic principles and characteristics of pipelinehot-tap inspection technology, focusing on the mechanical structure and electronic system of the in-line inspection tool.Site application shows that the pipeline hot-tap in-line inspection tool could effectively inspect typical metal loss, pipelinehot-tap with diameter over 5 mm, internal pipeline deformation and other defects. The inspection tool has active effect onguaranteeing the safe operation of pipelines and is worth popularizing.