Abstract: Pressure pipeline testing is crucial for ensuring the reliability of industrial production, requiring high standards of safety, convenience, and efficiency. To extend pipeline service life and prevent safety accidents, regular and effective testing and maintenance are necessary. However, due to the confined space inside pipelines and the harmful nature of the transmitted medium, manual testing was difficult. Traditional sampling testing and excavation methods have issues with stability, efficiency, and accuracy. This paper developed an ultrasonic phased array scanning testing system for the internal testing of pipelines based on crawling robot technology, addressing problems such as large equipment size, high cost, poor mobility, and inadequate coupling. A ring-shaped phased array probe, combined with a membrane water bag coupling device, was designed and tested in actual industrial pipelines. Results showed that this probe had high sensitivity, good signal-to-noise ratio in thick-walled pipes, and can accurately detect the location and size of defects. This system improved the efficiency and accuracy of pipeline inspection, meeting the high demands of industrial production.