An amorphous alloy Zr₆₀Al₁₀Co₂₂Ag₈ with high thermal stability was designed by introducing Co-Ag atom pair with positive mixing enthalpy and large atomic size difference and reducing Zr content. The as-spun amorphous alloy ribbons were prepared by vacuum single-roller melt-spinning method. The as-spun amorphous alloy ribbons were annealled at different temperatures. The structural characteristics and crystallization behaviors of the as-spun amorphous alloy ribbons were studied by X-ray diffraction (XRD), differential scanning calorimeter (DSC), and transmission electron microscope (TEM). The formation of clustered glass phase in Zr₆₀Al₁₀Co₂₂Ag₈ amorphous alloy and its effect on the thermal stability of the alloy were discussed. The results show that a fully amorphous phase (am) was formed in Zr₆₀Al₁₀Co₂₂Ag₈ as-spun alloy ribbons, and there were two exothermic peaks during heating. Clustered glass phase (C-glass) was formed after annealing at temperature just above T_x1. Even heating for up to 24 hours, the alloy ribbons still exhibited atomic disordered structure. The crystallization behavior was as follows: [am] → [C-glass] → [C-glass’ + Al₂CoZr₆ + AgZr + Ag₂Al] → [Al₂CoZr₆ + AgZr + AlZr₃] (where, C-glass" was the crystalline residual clustered glass phase). The existence of a large number of Co-Ag atom pairs with positive mixing enthalpy and large atomic size difference leaded to the difficulty of long range rearrangement of constituent elements, which induced the extremely high resistant to crystallization of clustered glass phase. This kind of amorphous alloys, which can form in clustered glass phase and resist crystallization at wide annealing condition, provide a new design method for new heat-resistant amorphous alloy.