Several common acoustic methods,such as pulse reflection ultrasonic testing,time difference of diffraction ultrasonic testing,conventional linear array ultrasonic phased array and fully focused phased array,are effective means to detect buried defects in butt welds of pressure equipment.However,there are many differences in application scope,detection sensitivity,resolution and defect measurement accu-racy. In view of the above differences,this paper first expounds the detection principle,compares the differences and advan-tages and disadvantages of several methods,then compares the detection results of 43 mm thick butt weld simulation test plate,and analyzes the results,so as to clarify the application of these methods,which provides certain technical support for the detection of buried defects in butt weld of pressure equipment in the future.