In order to study the influence of curing age and mineral admixture on the chloride ion binding ability of mortar,we compare the accuracy and reproducibility of different chloride ion concentration detection methods,determine the automatic potentiometric titration method as the best detection method,and research water-soluble chloride ions and acid-soluble chloride ions by automatic potentiometric titration for mortar samples of different curing ages and different mineral admixtures.The results show that the content of water-soluble chloride ions in mortar decreases with age,while the content of acid-soluble chloride ions has nothing to do with the length of age.The content of active SiO2 and active Al2O3 in mineral admixture determines the ability to solidify chloride ions.In the middle and long age (180d),the solidification ability of fly ash to chloride ion is greater than that of mineral powder.