Abstract: Fe_81-xCo_xZr₇Nb₂B₁₀(x = 2, 4, 6) amorphous alloys were prepared by single roller melt-spinning and annealed at different temperatures. The crystalline processes and magnetic properties of the alloys were studied by X-ray diff raction and vibrating sample magnetometer. The results show that when quenching speed reaches 30 m/s, Fe_81-xCo_xZr₇Nb₂B₁₀(x = 2, 4, 6) amorphous alloys are formed. The crystalline process of Fe₇₉Co₂Zr₇Nb₂B₁₀ is amorphous→amorphous +α-Fe→α-Fe + Fe₃Zr + Fe₂Nb_0.4Zr_0.6. The crystalline process of Fe₇₇Co₄Zr₇Nb₂B₁₀ is the same as Fe₇₅Co₆Zr₇Nb₂B₁₀: amorphous→amorphous +α-Fe→α-Fe + Fe₃Zr→α-Fe + Fe₃Zr + Fe₂Nb_0.4Zr_0.6.Increasing Co content restrains the nucleation of α-Fe and makes Fe₃Zr precipitate easy after annealing. The changing trends of magnetic properties of Fe_81-xCo_xZr₇Nb₂B₁₀(x = 2, 4, 6)  alloys are the same with increasing annealing temperature. Annealed below 530℃, special saturation magnetization (M_s) changes a little. After 530℃, M_s increases sharply. Annealed at 530℃, coercivity (H_c) reaches the minimum. After 530℃, H_c increases with increasing the annealing temperature.