Manganese oxalate is a novel conversion anode material for lithium ion batteries, but its low conductivity limits its application. To overcome this drawback, we report MnC2O4 microtubes prepared via a rapid assembly process in a T-type microchannel reactor. The X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images confirm that MnC2O4·2H2O microtubes are monoclinic α phase with a C2/c space group; MnC2O4 microtubes have a Pmna orthorhombic structure. As-synthesized MnC2O4 microtubes exhibit a high reversible capacity of 925 mAh⋅g−1 after 100 cycles at 1 A ⋅g−1. Even at an ultra-high current density of 5 A⋅ g−1, the anode MnC2O4 microtubes deliver a constant discharge capacity of 721 mAh⋅g−1 with a capacity retention of 97% on the 100th cycle. The improved performance can be attributed to the unique microtube structure composed of MnC2O4 nanoparticles, leading to faster electrode kinetics.