A study on the variation of Ca(OH)2 contents，CaCO3 contents as well as pH value in the carbonated concrete was carried out by chemical analysis test methods.The test results indicate that the variation of phase component is not completely consistent with that of the pH value in corresponding carbonation zone of concrete. The transect of carbonated concrete is composed of complete carbonation zone, semi carbonation zone with changing pH value, semi carbonation zone with stable pH value and non carbonation zone.