In order to improve the sensitivity and precision of ultrasonic testing and optimize the parameters of detecting process, it is important to fully understand the sound field formed by ultrasonic transducer. A laser visualization experimental platform for ultrasonic transducer sound field was set up. Using an ultrasonic transducer to emit ultrasonic wave in the specimen, we used laser speckle to receive the displacement of a point on the specimen surface over a period of time, and then obtained the displacements of particles in a certain area by scanning. Thereby a multi-time particle displacement field was formed to achieve the dynamic display of ultrasonic field. The diffusion of sound field of an ultrasonic transducer was detected by the system, and the detection results are consistent with theoretical calculations.