In the investigation,by means of a new surface self-nanocrystallization technique named SPRB ( SeverePlasticity Roller Burnishing) ,a gradient ultra-fine grain ( UFG) surface layer of a minimum grain size of about 300nmwas fabricated on pure iron.Then,the microstructure and the corrosion behavior of UFG surface layer wereanalyzed by means of TEM,XRD,SEM and electrochemical methods.The results show that ( 1) the outermost layerhardness of UFG iron is improved by more than 1.6 times in comparison with that of coarse grain ( CG) iron; ( 2) astrongly basal-textured grain orientation forms on the UFG surface and its micro strain is ( 0.313 ±0.017) %; ( 3) in 3.5% NaCl solution,the open circuit corrosion potential of UFG Fe is 24mV more than that of CG Fe in the positivedirection,and the corrosion current density decreases from 2.371 × 10^－5 A/cm² of CG Fe to 7.547 × 10^－8 A/cm² of UFG Fe; ( 4) in 6% FeCl₃ solution,the pitting rate of UFG Fe is about half as much as that of CG Fe; ( 5) thecorrosion resistance of UFG Fe is remarkably improved in comparison with that of CG Fe; and ( 6) the corrosion resistanceimprovement of UFG Fe is attributed to the surface grain refinement and the formation of the strongly basaltexturedgrain orientation.