The fabrication of Co–Li2S nanocomposite thin film is reported by pulsed laser deposition (PLD) for the first time. Li2S–Co nanocomposite thin film is used as storing Li electrodes that have led to promising electrochemical activity and good electrochemical performance. The releasing Li process from the as-deposited Li2S–Co nanocomposite thin films is confirmed by the ex situ high resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) measurements and may come from the decomposition of Li2S with and without the interaction of metal Co into CoS2 and S. The electrochemical reaction mechanism of Co–Li2S nanocomposite film electrode involving both the formation and decomposition of Li2S and the lithium extraction/insertion of CoS2 after the initial charging process is proposed. Our results demonstrate the advantages of using Co–Li2S nanocomposite in storage lithium materials.