Abstract: As the core component of the fusion reactor device, the weld bevel of the vacuum chamber requires full weld penetration, and the welding quality has strict requirements. In this paper, phased array ultrasonic inspection was used to control the quality of T-shaped welds in the vacuum chamber of a fusion reactor. However, the coarse crystalline organization of the weld and the complex structure of the vacuum chamber brought challenges to the phased array ultrasonic inspection. In this paper, the simulation calculation of the probe focus and focal column size was performed by CIVA software, and the results provided reference for the design of the inspection scheme, and then the full detection of defects was achieved by using the inspection scheme of fan sweeping excited by a double-sided array probe on the side of the web, and linear sweeping with an angle perpendicular to the fusion line excited by a line array probe on the outer side of the wing plate to inspect the demonstration block with typical weld defects. The inspection program can provide guidance for the inspection of T-welds in practical applications.