Dual-beam laser welding of titanium alloys for aircraft wall panels has gradually become the main connection method for high-performance fuselage structures. In view of the high requirements of wall panel welds, variety of defects, and large-scale welds, there is an urgent need for a non-destructive testing technology that takes into account the characteristics of high efficiency and high precision to ensure its safety performance. The high-frequency ultrasonic phased array inspection technology for the welding seam of aircraft wall panels is proposed in the research. The phased array ultrasonic inspection probe and the contrast test block are designed to perform fan-scan imaging detection of the internal and external defects of the weld seam, and then， the detection is verified by the metallographic method result. The research results show that the high-frequency ultrasonic phased array inspection technology can effectively detect the typical internal and external defects in the wall T–weld seam, including: non-fusion, pores, undercut, poor weld formation. The advantages of high efficiency, high precision, intuitive and reliable characteristics, make it suitable for non-destructive testing of aircraft wall welds.