Abstract: Ultrasonic phased array technology has a high sensitivity, resolution and signal to noise ratio, which makes it a hot research field of nondestructive testing. To improve the detection speed of ultrasonic phased array system, the key part of data transfer in ultrasonic phased array system is studied. The structure of self-developed ultrasonic phased array system is introduced. Three factors which include data bus, hardware driver and data reading program that determine the data transfer rate of system are described. To develop the system, PCI bus is chosen to be the data bus, DriverStudio is used to develop the PCI bus driver, and multi-core technology is applied to improve the efficiency of the data reading program. Experimental results show that using PCI bus technology and multi-core programming technology to develop the data transfer module of the ultrasonic phased array system can increase the data transfer rate speed of the system.