(Fe1-xCox)80Zr10B10 (x=0, 0.1, 0.2, 0.3) amorphous ribbons were prepared by the single roller melt-spinning and they are isothermally annealed at different temperatures. Thermal properties, microstructures and magnetic properties of the samples were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The results show that the thermal stability of the Co-free alloy is higher than that of the Co-containing alloys. However, there is little difference in the thermal stability of (Fe1-xCox)80Zr10B10 (x=0.1, 0.2, 0.3) alloys. The crystallization processes of Fe80Zr10B10 and Fe72Co8Zr10B10 alloys are similar. The crystallization processes of Fe64Co16Zr10B10 and Fe56Co24Zr10B10 alloys are similar. Coercivity (Hc) of the four alloys all increase firstly and then decrease. At 873 K, Hc all reaches the maximum.