Abstract: Based on the fatigue performance test of CHS K-joint used on the bridge,this paper studies the effectiveness of ultrasonic phased array detection technology on detecting the fatigue crack of pipe joints.During the test,the fatigue crack of steel tubular truss K-joint was monitored by ultrasonic phased array inspection equipment, and compared with the results of both strain measurement and slicing section of fatigue crack. The result shows that the quantitative and qualitative analysis on fatigue crack of joint can be achieved by ultrasonic phased array inspection technology.Fatigue crack detected by ultrasonic phased array inspection technology is earlier than that by visual observation. Thus, ultrasonic phased array testing can be used instead of conventional testing to detect the fatigue crack of the intersecting weld of the actual TKY tube joints used in actual structures.