Abstract: Because of traffic accidents, research on the rail stress has an important practical significance. This subject, on the basis of experiments , is to build a set of portable nondestructive stress testing system using the Barkhausen theory. The system which combines DSP and ARM makes full use of DSP that has high speed signal processing advantages, ARM that has friendly man-machine interactive control characteristics as well as the mature theory of Barkhausen. The device uses high sensitivity detection circuit with small volume and a reasonable signal acquisition circuit. It has the advantage of being light and portable, low power consumption and energy saving , so it will have great prospects in stress testing.