Abstract: Amorphous alloys, owing to their distinctive disordered microstructure, display intricate relaxation dynamics. Dynamic relaxation behavior is prevalent in amorphous alloys, and a deep understanding of its mechanism is essential for deconstructing the inherent microstructural heterogeneity of amorphous alloys. The addition of minor elements is one of the effective means to regulate the microstructure of amorphous alloys. In this study, the Cu₄₆Zr_47-xHf_xAl₇ (x = 0, 8) amorphous alloys, known for their excellent glass-forming ability, were used as model alloys. Utilizing dynamic mechanical analysis methods, the study investigated the variation of complex modulus concerning frequency and temperature, thereby exploring the impact of substituting Hf for Zr on dynamic relaxation. In the frequency spectrum of dynamic relaxation, the application of quasi-point defect theory elucidated that amorphous alloys exist in an iso-configurational state below the glass transition temperature (T_g), maintaining a constant concentration of quasi-point defects. Whereas, above T_g, the concentration of quasi-point defects increases linearly with the increase of temperature. The addition of Hf decreases the concentration of quasi-point defects in the iso-configurational state of glass system and suppresses atomic migration ability. Through continuous and discrete relaxation time distributions, it visually demonstrates the characteristics of dynamical heterogeneity of amorphous alloys. Regarding the temperature spectrum of dynamic relaxation, the introduction of Hf increases the mixed enthalpy of the glass system and suppresses the strength of β relaxation. Further analysis from an internal friction perspective indicates that the introduction of Hf not only elevates the activation difficulty of basic structural units related to β relaxation but also increases the activation energy of the entire β relaxation process.