Previous studies and experiments have been showed that elevated K+ concentration in the extracellular space can induce pathological discharge activities, such as epilepsy [1].The inward rectifier potassium channels (Kir4.1) in brain astrocytes is crucial for the maintenance of the extracellular potassium buffering [2].Therefore, studying the relations between kir4.1 channels and discharge activities through theoretical analysis methods will provide a strong guidance for understanding normal activities of the brain and treating epilepsy.This paper simulates the effect of the kir4.1 channels blocker by setting the kir4.1 current is equal to zero approximately.Our model reproduces several phenomena observed experimentally: Firstly, in contrast to control condition,long-lasting stimulation will induce the pronounced undershoot of the extracellular potassium concentration.Moreover, we found that K+ concentration in the extracellular space takes longer period to return to baseline after stimulation as kir4.1 channels is blocked.Furthermore, K+ concentration baseline in astrocyte is higher and it rises more slowly to a lower peak value compared with control condition.These results are all in good qualitative agreement with the experiments of [3;4].In addition, our results confirm the vital role of kir4.1 channels for extracellular potassium buffering by glia.