Because the continuous reorientation of magnetic moment induces magnetic domain wall irreversible jumps, a ferromagnetic material emits Barkhausen noise when it is in an alternating magnetic field. Because the Barkhausen noise size depends on the resistance when the magnetic domain wall moves, which means it depends on pinning site distribution and magnitude of pinning in the ferromagnetic material, so the material structure change will influence the wall's structure and movement, thereby changing the coercive field and other magnetic parameters of the material. We have treated 45# steel and 35CrMo steel by different heat treatments, and investigated the Barkhausen noise character given off by these samples in different magnetic fields, and we have found the relationship between different heat treatment conditions and Barkhausen noise released by different microstructures.