The dynamic mechanical relaxation behavior of Ti 36.2 Zr 30.3 Cu 8.3 Fe 4 Be 21.2 bulk metallic glass with good glass-forming ability was investigated by mechanical spectroscopy. The mechanical relaxation behavior was analyzed in the framework of quasi-point defects model. The experimental results demonstrate that the atomic mobility of the metallic glass is closely associated with the correlation factor χ. The physical aging below the glass transition temperature T g shows a non-Debye relaxation behavior, which could be well described by stretched Kohlrausch exponential equation. The Kohlrausch exponent aging reflects the dynamic heterogeneities of the metallic glass. Both concentration of "defects" and atomic mobility decrease caused by the in situ successive heating during the mechanical spectroscopy experiments.