The zero field NMR in pure iron gives information about domain walls because only the nuclei within domain wall are excited when r.f field is applied. This information can be used to better understand the saturation magnetization process qualitatively. For multidomain particles, the nuclear spins have different enhancement factors and relaxation times depending on their locations in the domain wall. We could estimate the internal strain energy of an unanneled Fe by its spin echo amplitude and line-width. In an anneled Fe, the spin-spin relaxation time was longer than spin-lattice relaxation time which is unusual. We measured the resonance frequency shift as a function of external field, and found that the demagnetization field of our sample was 6.4Kgauss. The relaxation time in domain was twice of that in domain wall and enhancement factor was 1/5.5 at 8Kgauss external field.