Abstract: Because of the special installation of the work-piece, it is necessary to perform ultrasonic testing of the elastic shaft with small diameter and long length by the end-incidence method. Due to the limitation of low sensitivity, serious side-wall interference,low resolution and large blind end area, conventional ultrasonic detection results are not so satisfied. In this paper, the ultrasonic phased array technique is used to control the focusing depth and scanning angle accurately, and the detection effect is very good.