Different morphology Mg-Al layered double hydroxides（Mg-Al LDHs）were synthesized by hydrothermal method, using magnesium nitrate and aluminum nitrate as raw material and urea as precipitation reagent. The prepared samples were characterized by SEM、XRD、BET and EDS etc., respectively. The adsorption performance of the LDHs and their calcined products for chloride ion were also investigated. The results showed that the rodlike Mg-Al LDHs could be synthesized by hydrothermal method when adding glycol. Hexagonal platelet-shaped and cube- shaped LDHs appeared when adding ethanol and tetrapropylammonium hydroxide. The specific surface area of the hexagonal platelet-shaped LDHs were 115.311m2/g, which had regularly and uniformly distributed morphology and can easily form a cross between support structure, showed good adsorption capability for chloride ion. The maximum adsorption capacity was 24.72 mg/g when the temperature was room temperature. The maximum adsorption capacity of the products calcined after 450 ℃ increased greatly, which was 96.07 mg/g in the same conditions. Optimal adsorption condition: the temperature is 35 ℃, the dosage of LDO-2 is 2.0 g/L, the value of pH is 8，the calcination temperature is 450 ℃.