The chloride binding capacity of fly ash concrete was studied by wet dry alternation method, then the distributions of free chloride content and total chloride content in concrete were obtained. The effect of fly ash on chloride binding capacity was discussed, and the change rule of chloride binding capacity with depth was analyzed. The results show that content of binding chloride in concrete increases due to the addition of fly ash. But chloride binding rate and relative chloride binding coefficient of fly ash concrete are less than the ones of ordinary concrete, and tend to decrease with the increase of fly ash content. With the increase of depth, the content of binding chloride first decreases and then increases, and the chloride binding capacity increases and then basically keeps stable.