Abstract: The softening rates of Fe-30%Ni alloy containing boron after 10% and 40% deformation at 1000℃ have been measured by a method of interrupted compression, the recrystallization process has also been evaluated. The moving velocity of the boundary of new recrystallizing grain which was growing into the deformed grains has been calculat-ed semi-quantitatively. By means of PTA technique, the abnormal segregation phenomenon on the moving boundary during recrystallization and the influence of pre-deformation have been investigated and the amount of B segregation on moving grain boundaries has been measured. Results indicate that the abnormal segregation of boundaries, when the new grains are growing, is concerned with the pre-deformation and the moving velocity of the bourdaries. This phenomenon is discussed by the grain boundary widening mechanism.