Abstract: For titanium alloy T-type welding structure of narrow wing plate, an ultrasonic phased array testing technology with multi-site scanning on web and wing plate was established,and the defect specimen was tested. On the basis of reducing the width of wing plate by mechanical processing, the defect detection effect of ultrasonic phased array testing was verified by radiographic testing, which offered reference for ultrasonic phased array testing of limited size T-type weld.