Abstract: Under conditions below the glass transition temperature (T_g=683 K), Zr₅₅Cu₃₀Al₁₀Ni₅ cast metallic glass sample underwent a 14 h annealing treatment at T_a=533 K to fully relax. Then, a rejuvenation treatment was performed with a 60 s holding at 656 K between T_a and T_g, followed by rapid quenching in ice water. The effects of enthalpy relaxation- rejuvenation treatment on the rejuvenation behavior and mechanical properties of Zr₅₅Cu₃₀Al₁₀Ni₅ bulk metallic glass were systematically investigated. The results show that the thermodynamic behavior of the as-cast metallic glass sample before T_g is an exothermic reaction. After annealing treated at 533K for 14 h, the thermodynamic behavior of the relaxed metallic glass manifests as an endothermic reaction. When the relaxed metallic glass sample undergoes rejuvenation treatment at 656 K for 60 s, its endothermic peak disappears, and the exothermic peak reappears, exhibiting a significant rejuvenation effect. This effect is driven by the enthalpy relaxation in the metallic glass. Compared to the cast metallic glass sample, the enthalpy relaxed-rejuvenated metallic glass sample demonstrates better plastic deformation ability.