This article introduces the entire process of acoustic emission detection of boiler water wall tubes. Due to the large curvature of the furnace tube surface, the sensor can only be installed in the area of the connecting plate between the furnace tubes, resulting in serious lateral attenuation. The distance between adjacent sensors in the lateral direction should be controlled within 40cm, but the longitudinal sensor can accept acoustic emission signals within the range of at least 80cm. Many acoustic emission positioning sources were found during the loading process. According to the standard of NB/T 47013.9-2012 “Nondestructive testing of pressure equipment Part 9: Acoustic emission testing”, the acoustic emission positioning sources were evaluated and classified. As a result, these signal sources are neither noise signals nor from crack propagation.