The deviation of radial distance to shorter value in EXAFS studies of metallic glass has been analysed in this paper. Simulation calculations showed that the current error theory can not explain the deviating-to-shorter phenomenon satisfactorily. By comparing the phase-shift function of amorphous state with that of crystalline state, we conclude that in the similar system the slope of amorphous phase-shift function may be different from that of crystalline phase-shift function. Normal EXAFS data processing without evaluating this kind of difference is also a cause of the radial distance deviating-to-shorter error in the EXAFS results. A simple method of correcting the slope of the phase-shift function of the reference sample (crystalline state) has been put forward and applied to the EXAFS data processing of Cu55Zr45 metallic glass. Results are well consistent with the results obtained from X-ray abnormal scattering measurement.