Mg-Al-NO3 hydrotalcite (p-LDH) was employed as a carrier for the controlled release of 5-Fluorouracil (5-FU). The p-LDH was pretreated by acid-pretreatment to gain a more stable material (a-LDH) in acid medium for oral administration. It demonstrated that the a-LDH had smaller crystal size, particle sizes and higher permanent charge density (σp) compared with that of the p-LDH by means of XRD, SEM, FT-IR, UV-vis DRS, TG-DSC, BET/BJH and other techniques. The FU/a-LDH and FU/p-LDH delivery systems were obtained using anion-exchange method. The in vitro 5-FU drug release studies showed that no burst release phenomenon was observed at the beginning of release tests. The in vitro 5-FU release behaviors of the delivery systems at initial pH 4.6 and 7.5 were studied which could be described by first-order and Bhaskas models. Combined with the XRD and FT-IR analyses of the solid residues of the FU/a-LDH and FU/p-LDH after the release, it was found that the dissolution mechanism was mainly responsible for the release behavior of the FU/p-LDH at initial 4.6, while the anion-exchange between intercalated 5-FU and phosphate anions mechanism was responsible for the FU/a-LDH at pH 4.6 and 7.5 as well as FU/p-LDH at pH 7.5. It is concluded that the hydrotalcites could be used as the basis of a tunable drug delivery carrier for 5-FU.