Abstract: This paper proposes an evaluating method for the effectiveness of leakage diagnosis by using quantitative index of model accuracy,aiming at the pressure sensitivity analysis-based leakage diagnosis method of the pipe network brought by model mismatch. FlowMaster software is used to establish the pipe network models with different accuracy of a real refrigerant system. Regarding the calibrated model as the benchmark of the pipe network,the improved Grey Relational Analysis(IGR2)is proposed to calculate model mismatch by estimating the similarity of pressure measurements between each model and the benchmark model. Thus,the indexes of quantitative model accuracy are achieved. Furthermore,Fault Diagnosis Success Percent(FDSP)is defined to calculate the effectiveness of leakage diagnosis. The leakage is diagnosed based on the models with different accuracy,and the effects of model accuracy on leakage diagnosis are obtained. Results illustrate that the effectiveness of this leakage diagnosis method is improved when the model becomes more accurate. When the refrigerant pipe network model accuracy is higher than 0.75,the FDSP is basically over 90% which shows that this leakage diagnosis is robust to model mismatch.