Abstract: Transmission electron microscopy (TEM) was applied to investigate the evolution of dislocation configuration and strain induced precipitation behavior during relaxation process after deformation in Fe-Ni-Nb-Ti-C-B alloy. Experimental results indicate that the dislocation density is very high and distribute randomly before relaxation. As the relaxation time increasing, dislocation cell swill form gradually by polygonization. The strain induced precipitation retards the progress. In the final relaxation stage, most dislo-cations get rid of pinning of precipitates and the cells have developed into subgrains with large size.