Abstract: Exposed outside yearly, the rails temperature shall be very different with climate change in seasons, resulting in thermal stress. In the using of Barkhausen noise(MBN) detection to test the thermal stress, the temperature changes have effects on the stress and the MBN itself, both of the two factors cause changes in MBN signal. To extract the information which reflects the stresschange, this paper introduced the design of MBN detection system. To guarantee the constant stress and temperature changes, the MBN signals in the laboratory were tested and the relationship between the features and changing temperature was discussed under the constant stress. It was found that, within the elastic range in the sample, MBN average, RMS, counts, peak, peak-width ratio decreased with the increase of temperature. However, the rate of change was different. Finally the features which have smaller changes with temperature changes and bigger changes with stress changes were found out. It explained the phenomenon which temperature changes have effect on the rail stress from the theory and analyze the impact of the residual stress, uneven distribution of temperature in the testing.