In order to achieve the green fluorescent switching of film materials constructed by pure inorganic cluster with green luminescence, a pure inorganic polyoxometalate constituent [Tb-4(H2O)(6)(beta-GeW10O38) (2)](12-) (TbGeW) was firstly chosen as the research object because it contains luminescent component Tb3+ and electrochromism component GeW together in a framework. Through the reasonable molecular design, three green luminescent composite films (PEI/TbGeW)(42), (PEI/P2W18/PEI/TbGeW)(42) and {(PEI/P2W18)(3)/PEI/TbGeW}(42) were successfully fabricated by layer-by-layer (LBL) assembly method. The prepared composite films were characterized by a series of technologies including UV-vis spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Cyclic Voltammetry (CV) and luminescence spectroscopy. The fluorescent switching performance of these composite films was investigated by an in situ spectroelectrochemical system consisted by electro-chemical workstation and fluorescence spectrophotometer. The investigated results indicated that the green fluorescent switching of film {(PEI/P2W18)(3)/PEI/TbGeW}(42) was thoroughly realized by the control of electrochemistry. (C) 2019 Elsevier Ltd. All rights reserved.