The variation of AC impedance spectra of three different types of concrete in the course of freezing and thawing cycle has been studied. The change of microstructure of concrete during freezing and thawing process, the mechanism of damage of concrete after freezing and thawing cycles can be known through the variation of their AC impedance spectra. AC impedance technique can also be applied to predict long term frost resistance of concrete after only very few cycles of freezing and thawing.