Abstract: In the ultrasonic phased array test process, in order to suppress grating lobes, reduce side lobes and minimize the width of main lobe, the influence of array element number, interelement spacing, steering angle and element width on beam directivity and ultrasonic pressure field produced by a linear phased array transducer were systematically discussed, through the emulation mode. The relation of beam directivity and dimensional parameters was duced for the optimizing designing of linear phased array transducer.