Abstract: The principle of spatial compound imaging and its advantages were introduced and experiments by using the spatial compounding imaging to improve the image quality were carried out. Test results show that the spatial compound imaging technology can reduce the noise in polyethylene pipe welding imaging in ultrasonic testing, expand the testing area, reduce the blind area and artifacts, and thus can improve the contrast and resolution image. And in the PE pipeline welding the spatial compound imaging technique using phased array inspection was applied in engineering practice and achieved good results, and the image quality and defect detection ability were improved.