Since　magnetic　Barkhausen　noise　is　very　sensitive　to　the　change　of　the　stress　or　residual　stress　level　in　components,　it　is　feasible　to　detect　the　stress　or　residual　stress　profile　along　the　depth　direction　by　the　magnetic　Barkhausen　noise　method.　An　engineering　approach　was　used　to　validate　a　theoretical　model　describing　the　relationship　between　magnetic　Barkhausen　noise　and　stress　magnitude.　To　generate　stress　gradients　in　the　specimen　of　Q235　steel　under　different　deflections,　the　four-point　bending　device　was　used.　Then　the　detected　signals　obtained　in　the　experiment　were　divided　into　different　sub-bands　to　evaluate　the　stress　at　different　depths.　The　testing　depth　was　set　to　be　around　100　mu　m　due　to　the　rapid　exponential　attenuation　of　the　noise　signals.　In　the　experiments,　the　sub-band　energy　density　showed　sensitive　as　the　loading　displacement　increasing.　The　experimental　results　showed　that　the　signal　energy　was　also　sensitive　to　the　plastic　deformation　of　the　material.　Within　the　depth　of　100　mu　m,　the　stress　change　was　very　small.　The　final　experimental　results　showed　that　even　under　such　small　stress　variations,　it　is　sensitive　and　feasible　to　use　the　magnetic　Barkhausen　noise　energy　to　characterise　the　change　of　stress　gradients.