The accumulation of extracellular potassium(K+)concentration induces astrocytes membrane depolarization,which causes the voltage-gated calcium channel(VGCCs)current flow into astrocyte and increases the level of calcium concentration in astrocyte,thus enhancing the positive feedback effect of astrocyte on neuron.In this work,we presented a neuron-astrocyte coupled model consisting of ions concentration dynamics.Our model validated experimental recordings that Ca2+ influx through VGCCs is a major factor in the increase of Ca2+ concentration in astrocyte and revealed the internal mechanism that enhanced VGCCs current could induce spontaneous epileptic discharges in the absence of external stimulus input.The results in this work will provide an explanation for Ca2+ metabolism disorders of astrocytes can induce spontaneous epilepsy discharges.