In this study, ultrasonic testing (UT) is adopted for the non-destructive testing (NDT) of the China Fusion Engineering Test Reactor (CFETR) vacuum vessel (W) welding. Coarse grain and anisotropy of austenitic stainless steel welding pose great challenges on traditional UT and linear probes of phased array ultrasonic testing (PAUT) in terms of sensitivity and accuracy. An automatic PAUT system of dual matrix array probe has been recently developed and qualified in ASIPP. In this paper, key parameters of the system and test results obtained on demonstration blocks are introduced. Test results imply high sensitivity and efficiency of the automatic PAUT system, which will be further testified on the NDT of CFETR VV welding.