Four three‐dimensional heterometallic coordination polymers, [Ln2Cu4I3(IN)7(H2O)]n (1, 2) and [LnCu3.5I3(IN)3.5(H2O)3]n·nH2O (3, 4) [HIN = isonicotinic acid, Ln = Nd (1), Gd (2), La (3), Eu (4)] were hydrothermally synthesized by using lanthanide oxides, isonicotinic acid, copper chloride, and potassium iodide. The different molar ratio of raw materials results in two distinct types of three‐dimensional frameworks of compounds 1–4. The structure of compounds 1 and 2 are constructed by the layer modules of [Ln2(IN)7(H2O)]nn– and Cu4I3 clusters, whereas that of compounds 3 and 4 are built by dimeric Ln2(IN)6(H2O)6 and layered polymeric [Cu7I6]nn+ units.