Abstract: The （FeCo）₈₅Si_0.5B₁₁C_2.5P₁（at%） amorphous alloy was annealed in the presence of tensile stress with isothermal tension annealing equipment and the DC-bias field H_0.98was defined to compare the DC tolerance property.The effects of annealing temperature,isothermal time,tensile stress and cooling rate on the magnetic properties and structure of alloy were investigated.The results show that the DC tolerance property and the core loss of the alloy increase with the increase of annealing tension and isothermal time at 300-400℃.After being kept at 350℃for 20 min,the DC-bias field H_0.98and core loss P_cmof alloy are 440 A/m and 1749 W/kg （300 m T,100 k Hz）,respectively.When the isothermal time increases from 10min to 60 min in the tension annealing process,the DC bias field H_0.98of the alloy basically remains at 400-450 A/m steadily.At the same time,after 375℃tension annealing,the DC bias ability decreases and the loss value increases with the increase of annealing tension and cooling rate.In addition,after tension annealing,the alloy forms a lamellar anisotropy structure parallel to the band axis and tension direction.