In order to explore the influence of different array element parameters on the acoustic field of phased array ultrasonic array transducer， based on the basic principle of phased array ultrasonic detection and acoustic field radiation theory， the numerical simulation analysis is carried out by using MATLAB software， and the radiation acoustic field model is established， and the directivity and acoustic field of array transducer under different parameters are analyzed. The comparative analysis method is used to analyze the influence of various parameters of the array element on the beam quality， focusing range and imaging effect. The conclusion is that the imaging resolution will be too low if the array center frequency is too small， and the acoustic field penetration is weak and the detection depth is shallow. The increase of the number of array elements can significantly improve the imaging effect， but it also greatly increase the cost. The width of the array element will increase when the center distance of the array element increases from 0.1 to 0.3， the imaging effect is significantly improved， and then to 0.6， the improvement is not obvious. The increase of the array center distance will improve the focusing accuracy and imaging effect， but when it is more than 0.8， the imaging effect drops sharply. When the deflection angle is less than 30°， the imaging effect is stable and clear. When the deflection angle is too large， the imaging effect will be significantly worse. If the focusing depth is too small， the acoustic beam focusing property is poor， and the imaging effect is not good， and the focusing depth is greater than the detection surface， the imaging effect is good. This conclusion has certain practical significance for guiding the actual ultrasonic phased detection.