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The microstructure, V-I characteristics, and stability of ZnO-Pr6O11-CoO-Cr2O3-Y2O3-based varistor ceramics were investigated with cooling rate in the range of 2~8℃/min. The cooling rate relatively weakly affected the microstructure, the varistor voltage, and the leakage current in the V-I characteristics. But the nonlinear exponent relatively strongly affected by cooling rate. The cooling rate also greatly affected the stability of V-I and dielectric characteristics for DC accelerated aging stress. On the whole, the varistors cooled with 4℃/min exhibited the highest performance in the densification, nonlinearity, and stability. Especially, they exhibited a high stability, in which the variation rate of the varistor voltage(V1mA), the nonlinear exponent(α), and the dissipation factor(tanδ) is -1.4%, -4.9%, and +60.0%, respectively, under DC accelerated aging stress such as 0.95 V1mA/150℃/12 h)