Abstract: A design based on ultrasound probe wedge used for longitudinal defects of pipeline was referred. The delay of the ultrasound in the plexiglass was used for the realization of ultrasonic energy convergence. At the same time, related experiments were done with the self-developed ultrasonic dynamic photo-elastic processing systems and a plexiglass ring with artificial defects. Through experiments a lot of photos were got, showing that the method used to detect defects of vertical pipe was feasible.