Abstract: Topological insulators (TIs) are a new class of quantum matter which have attracted extensive interest recently. Nanometer thick TI thin films not only exhibit novel physical properties but also are useful for developing TI-based planar devices. Taking Bi2Se3 as an example, we report the molecular beam epitaxy growth of the Bi2Se3 family of TI thin films and the thickness dependent behavior of their band and spin structures and topological characteristics. The results provide information on the artificial control of the electronic structures and physical properties of TIs.