Abstract: The austenite structure of weld is characteristics of coarse grain and anisotropy. There are some limitations and deficiencies in linear array phased array, conventional ultrasonic and radiographic testing technology. Based on DMA (dual matrix array) phased array probe and using Israel ISONIC 2009 phased array detector, with NB/T 47013. 3-2015 appendix I No. 3 reference block being for B-scan and C-scan imaging, test result for 40 mm thick simulation test block were compared and analyzed. The results show that the ultrasonic phased array detection method based on DMA probe has high feasibility in thick walled austeniticed butt weld inspection, and can be used in practical inspection.