The stability and the soft magnetic properties of amorphous Fe52Co34Hf7B6Cu1 alloys have been investigated in this paper. Amorphous Fe52Co34Hf7B6Cu1 alloys ribbons are prepared by single-roller-quenching method. The differential thermal analysis (DTA), X-ray diffraction (XRD), Mössbauer Spectroscopy, transmission electron microscope (TEM) and vibrating sample magnetometer (VSM) were used for characterizing microstructures, soft magnetic properties, and evaluating the influence of adding manners of B on the stability of as-quenched specimens. The XRD curve shows a wide dispersion of peak, the TEM diffraction ring was dispersed cyclic, the pattern of the matrix was homogeneous, and the Mössbauer spectrum of as-quenched alloy presents a typical broadened and overlapped sextet, which confirms the as-quenched alloy in fully amorphous state. The DTA results showed the activation energy of Fe52Co34Hf7B6Cu1 alloy is 299.7KJ/mol. When pure B is replaced by FeB in preparing amorphous Fe52Co34Hf7B6Cu1 alloys, the activation energy reduced to 293.3 KJ/mol,and the soft magnetic property is decline according VSM results.