Abstract: In order to further clarify the influence of stress on the fatigue test performance of the materials, the piezomagnetic field was introduced as a new damage indicator. A series of stress-controlled tests were carried out on 30Cr alloy steel. A fluxgate flux meter was used to test the surrounding magnetic field of the specimen during the whole loading process. The evolution of the piezomagnetic field under cyclic stress was studied after the specimen has experienced different maximum stresses. Besides, the characteristics of magnetic field in different degrees of fatigue damage were analyzed. The analysis results show that the historical maximum stress leads to dislocations and microcracks in the material, which has an obvious effect on the subsequent fatigue loading.