Abstract: In this paper,the conduction mechanism in Ge₂Sb₂Te₅ based phase change memory has been studied.Considering the field-induced nonlinear decrease of activation energy observed in the experiments,as well as the effect of crystallization which results in an increase of the hopping distance,a model for the shift in the effective conduction band edge has been proposed.Thus a modified model for the current mechanism in Ge₂Sb₂Te₅ based phase change memory has been built.Calculation results demonstrate that the decrease of activation energy with applied voltage obeys a hyperbolic cotangent form,which are verified with the measured data.Temperature effect has also been contained in this model.The results demonstrate that hopping distance is inversely proportional to the temperature.Calculated current-voltage results for the Ge₂Sb₂Te₅ based phase change memory show good agreement with the temperature dependence and the I-V characteristics observed in the experiments.