Fe-based metallic glasses(MGs) with excellent soft magnetic properties are applicable in a wide range of electronic industry. We show that the cryogenic thermal cycle has a sensitive effect on soft magnetic properties of Fe_(78)Si_9B_(13) glassy ribbon. The values of magnetic induction(or magnetic flux density) B and H_c coercivity c show fluctuation with increasing number of thermal cycles. This phenomenon is explained as thermal-cycle-induced stochastically structural aging or rejuvenation which randomly fluctuates magnetic anisotropy and, consequently, the magnetic induction and coercivity. Overall,increasing the number of thermal cycles improves the soft magnetic properties of the ribbon. The results could help understand the relationship between relaxation and magnetic property, and the thermal cycle could provide an effective approach to improving performances of metallic glasses in industry. Fe-based metallic glasses (MGs) with excellent soft magnetic properties are applicable in a wide range of electronic industry. We show that the cryogenic thermal cycle has a sensitive effect on soft magnetic properties of Fe_ (78) Si_9B_ (13) glassy ribbons. The values ​​of magnetic induction (or magnetic flux density) B and H_c coercivity c show fluctuation with increasing number of thermal cycles. This phenomenon is explained as thermal-cycle-induced stochastically structural aging or rejuvenation which produce fluctuating magnetic anisotropy and, Overall, increasing the number of thermal cycles improves the soft magnetic properties of the ribbon. The results could help understand the relationship between relaxation and magnetic property, and the thermal cycle could provide an effective approach to improve performances of metallic glasses in industry.