Abstract: The metal magnetic memory testing method can diagnose stress concentrate zone of the ferromagnetic which the damage is going to appear in advance, thus realize to predict destruction. The magnetic memory signal distributing of the ferromagnetic have been changed by different stress state. A passel of steel bar have been made to primary discuss the embedded relation of magnetic signal distributing and stress field under static tension experiment before and after loading, the tension course and offloading and during the tension course.