The parabolic curve fitting method is used to calculate the peak value and the corresponding time coordi-nate of short-circuit current waveform in high power tests. It is proved theoretically that the current value at the mid-point of the two adjacent peaks in the short-circuit current waveform is approximately equal to the DC component atthis time. A algorithm to calculate the DC time constant

the RMS value of AC（fundamental）component and the per-centage value of DC component is given accordingly. Using the standard short-circuit current waveform provided bySTL

the algorithms of this paper and the existing ones are compared and tested. Test results verify the accuracy ofthe algorithms in this paper

and show that using only three peak points does not significantly reduce the accuracy ofthese algorithms when calculating short-circuit current waveform parameters with constant AC components. The rela-tive expanded uncertainties of these algorithms in calculating the crest value

the DC time constant

the RMS valueof AC component and the percentage value of DC component are 0.03%

0.22%

0.39%

and 0.76% respectively

which were obtained by calculating the parameters of the STL standard waveforms at each peak point

whose DCtime constants different

frequency and the RMS value of AC component change over time.