Abstract: A calculation method are presented, which can be used to compute displacement field of direct wave in a pipe emitted by a new ultrasonic phased array on the inner surface of a circular stage that is used to detect the circumferential flaws inside a pipe. According to Rayleigh integration and stationary phase method, the time delay law is designed and the theoretical research on refraction of displacement emitted by the new phased array in a pipe is conducted. At last, the effect on the radiated displacement distribution in the pipe with different parameters of the focusing phased array is discussed and analyzed. It is shown that the model and the calculation method can effectively research the character of radiated displacement field of this new phased array, and can be used to provide guidance for phase array design.