Abstract: Ultrasonic phased array technique can achieve flexible, controllable synthesized ultrasound beam by exciting each element of an ultrasonic array transducer with independent phased delay to detect the whole part of component. Phased array ultrasonic can accomplish dynamic focusing, obtain visual image, inspect component of complex geometry. Recently, the ultrasonic phased array technique has been highly recognized in NDT research domain and it has been used successfully in medical and industry application. In this thesis, a numerical simulation model is established to investigate the influences of parameters of linear phased array transducers on beam steering based on the principle of ultrasonic phased array which will be basic results for UPA. Using this approach, we can clearly know the features of controlling synthesized ultrasound beam of ultrasonic phased array.