MnO offers remarkably high theoretical capacity based on conversion reaction for lithium-ion batteries (LIBs). However, the low electronic conductivity and large volume changes of MnO have severely limited its applications. Due to the high conductivity of carbon nanotubes (CNTs), we synthesized a three-dimensional (3D) interconnected MnO/CNTs composite by a step-by-step method to solve the above issues. The obtained 3D interconnected MnO/CNTs composite has the advantages of high capacity of MnO and the excellent conductivity of CNTs, in which CNTs were connected with each other to form an interconnected network for the embedding of nanosized MnO particles. As a consequence, the prepared 3D interconnected MnO/CNTs composite shows a high capacity of 992 mA h g−1 at 0.2 A g−1 after 150 cycles and 893 mA h g−1 at 0.5 A g−1 after 300 cycles, demonstrating the potential of promising anode material for LIBs.