Based on analysis and improvement of simple response method(SRM) and Weibull reliability method for calibration intervals of test system

and by taking into account fault decisions on the calibration process

the decision risks on verification of test system were resolved.In this paper

related national measurement standards on reliability index of test system were firstly introduced

then some usual calibration interval determination methods were also discussed

and furthermore the reliability probability functions for observational value of test reliability were given.By synthesizing different parameters with principal component analysis(PCA) method

the estimation values of the optimal calibration interval were corrected.Lastly

the results of verification on digital multimeter(DMM) measurement channel in automatic test system(ATS) show that the calibration intervals optimization methods are feasible.